From e85fc6b467e79f7679ec8751d411889bf37bac76 Mon Sep 17 00:00:00 2001
From: Fedor <fedor@mail.ru>
Date: Sat, 1 Jun 2024 19:21:49 +0300
Subject: [PATCH] 68.14.2 - dom

---
 dom/animation/KeyframeUtils.cpp               |   6 +-
 dom/base/AnonymousContent.cpp                 |   1 +
 dom/base/AnonymousContent.h                   |  15 +-
 dom/base/BodyConsumer.cpp                     |   3 +
 dom/base/BorrowedAttrInfo.cpp                 |   6 +-
 dom/base/CustomElementRegistry.cpp            |  41 +-
 dom/base/CustomElementRegistry.h              |  22 +-
 dom/base/DOMMatrix.cpp                        |  20 +-
 dom/base/DOMMatrix.h                          |  19 +-
 dom/base/Document.cpp                         | 119 ++--
 dom/base/Document.h                           |  22 +-
 dom/base/Element.cpp                          |   3 +-
 dom/base/Element.h                            |  16 +-
 dom/base/EventSource.cpp                      |   1 -
 dom/base/IdentifierMapEntry.h                 |  11 +-
 dom/base/ImageEncoder.cpp                     |   7 +-
 dom/base/Link.cpp                             |  30 +-
 .../{nsStyleLinkElement.cpp => LinkStyle.cpp} | 150 ++---
 dom/base/LinkStyle.h                          | 285 +++++++++
 dom/base/ResizeObserver.cpp                   |  94 ++-
 dom/base/ResizeObserver.h                     |  31 +-
 dom/base/ResizeObserverController.cpp         |   7 -
 dom/base/ResizeObserverController.h           |   4 -
 dom/base/ResponsiveImageSelector.h            |   1 -
 dom/base/ShadowRoot.cpp                       |   1 -
 dom/base/StructuredCloneHolder.h              |   5 +-
 dom/base/ThirdPartyUtil.cpp                   |   4 +-
 dom/base/TimeoutManager.cpp                   |   2 +-
 dom/base/moz.build                            |   5 +-
 dom/base/nsAttrValue.cpp                      |   2 +-
 dom/base/nsContentPolicy.cpp                  |   4 +-
 dom/base/nsContentPolicyUtils.h               |  59 +-
 dom/base/nsContentSink.cpp                    | 167 +++---
 dom/base/nsContentSink.h                      |  32 +-
 dom/base/nsContentUtils.cpp                   |  92 +--
 dom/base/nsContentUtils.h                     |   9 +-
 dom/base/nsDOMDataChannel.cpp                 |  33 +-
 dom/base/nsDOMMutationObserver.h              |  29 +-
 dom/base/nsDocumentEncoder.cpp                |   3 +
 dom/base/nsFrameMessageManager.cpp            |  16 +-
 dom/base/nsFrameMessageManager.h              |   4 +-
 dom/base/nsGlobalWindowInner.cpp              |   7 -
 dom/base/nsGlobalWindowInner.h                |   4 -
 dom/base/nsGlobalWindowOuter.cpp              |   2 +-
 dom/base/nsGlobalWindowOuter.h                |   1 -
 dom/base/nsIContentPolicy.idl                 |  24 +
 dom/base/nsINode.cpp                          |   6 +-
 dom/base/nsINode.h                            |   8 +
 dom/base/nsIStyleSheetLinkingElement.h        | 204 -------
 dom/base/nsImageLoadingContent.cpp            |   4 +-
 dom/base/nsNodeInfoManager.cpp                |   2 +-
 dom/base/nsObjectLoadingContent.cpp           |  17 +
 dom/base/nsQueryContentEventResult.cpp        |   8 +-
 dom/base/nsStyleLinkElement.h                 | 139 -----
 dom/base/nsTreeSanitizer.cpp                  |  11 +-
 dom/bindings/Bindings.conf                    |   1 +
 dom/bindings/Codegen.py                       |   4 +-
 dom/bindings/Nullable.h                       |   8 +-
 dom/bindings/Record.h                         |   7 +-
 dom/bindings/ToJSValue.cpp                    |  27 +
 dom/bindings/ToJSValue.h                      |  34 +-
 dom/bindings/parser/WebIDL.py                 |   4 +-
 dom/cache/DBSchema.cpp                        |   6 +-
 dom/chrome-webidl/ChannelWrapper.webidl       |   5 +-
 dom/events/Clipboard.cpp                      |   2 +
 dom/fetch/Fetch.h                             |   2 -
 dom/fetch/FetchDriver.cpp                     | 165 +++++-
 dom/fetch/FetchDriver.h                       |  20 +-
 dom/fetch/FetchUtil.cpp                       |   1 +
 dom/fetch/InternalRequest.cpp                 |   7 +
 dom/fetch/InternalRequest.h                   |   6 +-
 dom/fetch/Request.cpp                         |  40 +-
 dom/fetch/Request.h                           |   6 +
 dom/fetch/tests/crashtests/1664514.html       |   6 +
 dom/fetch/tests/crashtests/crashtests.list    |   3 +-
 dom/fetch/tests/crashtests/url.url            |   5 +
 dom/file/ipc/FileCreatorParent.cpp            |   7 +-
 dom/file/uri/BlobURLProtocolHandler.cpp       |  10 +-
 dom/filehandle/ActorsParent.cpp               |  26 +-
 dom/filehandle/ActorsParent.h                 |   4 +-
 dom/filesystem/Directory.cpp                  |   8 +-
 dom/filesystem/FileSystemBase.cpp             |   9 +-
 dom/flex/Flex.h                               |   2 +-
 dom/html/HTMLDialogElement.cpp                | 100 ++++
 dom/html/HTMLDialogElement.h                  |   3 +
 dom/html/HTMLFormElement.cpp                  |   3 +-
 dom/html/HTMLFormSubmission.cpp               |   1 +
 dom/html/HTMLImageElement.cpp                 |  18 +-
 dom/html/HTMLImageElement.h                   |  10 +
 dom/html/HTMLInputElement.cpp                 |   1 +
 dom/html/HTMLLegendElement.cpp                |   1 +
 dom/html/HTMLLinkElement.cpp                  | 126 ++--
 dom/html/HTMLLinkElement.h                    |  31 +-
 dom/html/HTMLMediaElement.cpp                 |   7 +-
 dom/html/HTMLMenuElement.cpp                  |   7 +-
 dom/html/HTMLStyleElement.cpp                 |   7 +-
 dom/html/HTMLStyleElement.h                   |   6 +-
 dom/html/HTMLTrackElement.cpp                 | 144 +++--
 dom/html/HTMLTrackElement.h                   |  14 +-
 dom/html/TextTrackManager.cpp                 |   4 +-
 dom/html/moz.build                            |   1 +
 dom/html/nsHTMLContentSink.cpp                |   2 -
 dom/html/test/dialog/mochitest.ini            |   7 +
 .../dialog/test_cancelDialogByEscape.html     |  63 ++
 .../dialog/test_dialog_cancel_events.html     |  56 ++
 .../test_dialog_cancel_preventDefault.html    |  56 ++
 .../test_dialog_keydown_preventDefault.html   |  56 ++
 dom/html/test/file_cookiemanager.js           |   2 +-
 dom/ipc/ContentParent.cpp                     |   2 +
 dom/ipc/WindowGlobalChild.cpp                 |   1 +
 .../en-US/chrome/security/csp.properties      |  19 -
 dom/localstorage/ActorsParent.cpp             |   4 +-
 dom/localstorage/LSSnapshot.cpp               |  16 +-
 dom/manifest/test/mochitest.ini               |   3 +-
 .../test_link_relList_supports_manifest.html  |  47 ++
 dom/media/TextTrack.cpp                       |  35 +-
 dom/media/TextTrack.h                         |   2 +
 dom/media/WebVTTListener.cpp                  |  61 +-
 dom/media/WebVTTListener.h                    |   9 +
 dom/media/gmp/GMPServiceParent.cpp            |   2 +-
 dom/media/test/test_bug883173.html            |  70 +--
 dom/media/test/test_bug895091.html            |  80 +--
 dom/media/test/test_texttrack.html            | 256 ++++----
 dom/media/test/test_texttrack_moz.html        | 104 ++--
 dom/media/test/test_texttrackcue.html         | 519 +++++++++--------
 dom/media/test/test_texttrackregion.html      |  89 ++-
 dom/media/test/test_trackelementevent.html    | 108 ++--
 dom/media/webaudio/AudioWorkletImpl.h         |   4 +
 dom/media/webaudio/WebAudioUtils.cpp          |   1 +
 dom/media/webvtt/WebVTTParserWrapper.jsm      |   6 +
 dom/media/webvtt/nsIWebVTTParserWrapper.idl   |   5 +
 dom/midi/MIDIUtils.cpp                        |   9 +-
 dom/network/TCPServerSocket.cpp               |   1 +
 dom/notification/Notification.cpp             |   6 +-
 dom/performance/PerformanceTiming.cpp         |   2 +-
 .../base/nsPluginDirServiceProvider.cpp       | 306 +++++++++-
 dom/plugins/base/nsPluginDirServiceProvider.h |   6 +
 dom/plugins/base/nsPluginHost.cpp             |  81 ++-
 .../base/nsPluginStreamListenerPeer.cpp       |   2 -
 .../PresentationDeviceManager.cpp             |   1 +
 dom/presentation/PresentationRequest.cpp      |  17 +-
 dom/presentation/PresentationSessionInfo.cpp  |  21 +-
 .../PrototypeDocumentContentSink.cpp          |  33 +-
 dom/prototype/PrototypeDocumentContentSink.h  |   3 +-
 dom/push/PushManager.cpp                      |   1 +
 dom/push/test/xpcshell/head-http2.js          |  12 -
 dom/quota/ActorsParent.cpp                    |  27 +-
 dom/script/ScriptKind.h                       |  16 +
 dom/script/ScriptLoadHandler.cpp              |  18 +-
 dom/script/ScriptLoadHandler.h                |   3 +
 dom/script/ScriptLoadRequest.cpp              |  27 +-
 dom/script/ScriptLoadRequest.h                |  24 +-
 dom/script/ScriptLoader.cpp                   |  53 +-
 dom/script/ScriptLoader.h                     |   2 +
 dom/script/moz.build                          |   1 +
 dom/security/CSPEvalChecker.cpp               |   4 +-
 dom/security/nsCSPParser.cpp                  |   9 +-
 dom/security/nsCSPService.cpp                 |   2 +-
 dom/security/nsCSPUtils.cpp                   |  22 +
 dom/security/nsContentSecurityManager.cpp     |  24 +-
 dom/security/nsMixedContentBlocker.cpp        |  19 +-
 dom/security/test/csp/file_bug1505412.sjs     |  36 ++
 .../test/csp/file_bug1505412_frame.html       |  14 +
 .../csp/file_bug1505412_frame.html^headers^   |   1 +
 .../test/csp/file_bug1505412_reporter.sjs     |  18 +
 .../test/csp/file_link_rel_preload.html       |  17 +
 .../test/csp/file_object_inherit.html         |  21 +
 dom/security/test/csp/mochitest.ini           |  12 +
 dom/security/test/csp/test_bug1505412.html    |  50 ++
 .../test/csp/test_link_rel_preload.html       |  77 +++
 .../test/csp/test_object_inherit.html         |  30 +
 dom/smil/SMILAnimationFunction.cpp            |   2 +-
 dom/smil/SMILCSSProperty.cpp                  |   4 +-
 dom/svg/SVGAnimatedNumberList.cpp             |   2 +-
 dom/svg/SVGAnimatedPointList.cpp              |   2 +-
 dom/svg/SVGElement.cpp                        |   1 +
 dom/svg/SVGStyleElement.cpp                   |   7 +-
 dom/svg/SVGStyleElement.h                     |  10 +-
 .../ajax/offline/browser_disableAppcache.js   | 121 ----
 dom/webbrowserpersist/nsWebBrowserPersist.cpp |   7 +-
 dom/webidl/CustomElementRegistry.webidl       |   2 +-
 dom/webidl/ElementInternals.webidl            |   3 +-
 dom/webidl/HTMLElement.webidl                 |   2 +-
 dom/webidl/HTMLImageElement.webidl            |   2 +
 dom/webidl/HTMLLinkElement.webidl             |   4 +
 dom/webidl/OfflineResourceList.webidl         |   2 +-
 dom/webidl/ResizeObserver.webidl              |   8 +-
 dom/webidl/Window.webidl                      |   2 +-
 dom/websocket/WebSocket.cpp                   |   6 +-
 dom/workers/RuntimeService.cpp                |  33 +-
 dom/workers/ScriptLoader.cpp                  |   1 +
 dom/workers/WorkerLoadInfo.cpp                |  15 +-
 dom/workers/WorkerLoadInfo.h                  |   7 +-
 dom/workers/WorkerPrivate.cpp                 |  51 +-
 dom/workers/WorkerPrivate.h                   |   5 +-
 .../remoteworkers/RemoteWorkerChild.cpp       |   9 +-
 dom/worklet/Worklet.cpp                       |  33 +-
 dom/worklet/Worklet.h                         |   3 +-
 dom/worklet/WorkletImpl.h                     |   2 +
 dom/xhr/XMLHttpRequestMainThread.cpp          | 130 ++++-
 dom/xhr/XMLHttpRequestMainThread.h            |  17 +-
 dom/xml/CDATASection.cpp                      |   2 +-
 dom/xml/ProcessingInstruction.cpp             |  22 +-
 dom/xml/ProcessingInstruction.h               |  21 +-
 dom/xml/XMLDocument.cpp                       |   1 +
 .../XMLStylesheetProcessingInstruction.cpp    |  17 +-
 dom/xml/XMLStylesheetProcessingInstruction.h  |  23 +-
 dom/xml/nsXMLContentSink.cpp                  |  41 +-
 dom/xml/nsXMLContentSink.h                    |   4 +-
 dom/xml/nsXMLElement.h                        |   2 +-
 dom/xml/nsXMLFragmentContentSink.cpp          |  10 +-
 dom/xslt/base/txExpandedNameMap.h             |   4 +-
 dom/xslt/base/txList.cpp                      |  37 +-
 dom/xslt/base/txList.h                        |  10 +-
 dom/xslt/crashtests/1589930.xml               |  10 +
 dom/xslt/crashtests/crashtests.list           |   1 +
 dom/xslt/xpath/XPathEvaluator.cpp             |  32 +-
 dom/xslt/xpath/XPathEvaluator.h               |   1 -
 dom/xslt/xpath/XPathExpression.cpp            |  20 +-
 dom/xslt/xpath/XPathExpression.h              |   9 +-
 dom/xslt/xpath/XPathResult.cpp                |   2 +-
 dom/xslt/xpath/XPathResult.h                  |   1 -
 dom/xslt/xpath/txCoreFunctionCall.cpp         |   1 -
 dom/xslt/xpath/txExpr.h                       |  46 +-
 dom/xslt/xpath/txExprParser.cpp               | 198 ++++---
 dom/xslt/xpath/txExprParser.h                 |   6 +-
 dom/xslt/xpath/txExprResult.h                 |   1 -
 dom/xslt/xpath/txFilterExpr.cpp               |   9 +-
 dom/xslt/xpath/txForwardContext.h             |   1 -
 dom/xslt/xpath/txNodeSetContext.h             |   1 -
 dom/xslt/xpath/txPathExpr.cpp                 |  13 +-
 dom/xslt/xpath/txResultRecycler.h             |   1 -
 dom/xslt/xpath/txXPathNode.h                  |   1 -
 dom/xslt/xpath/txXPathOptimizer.cpp           |   7 +-
 dom/xslt/xslt/txBufferingHandler.cpp          |   4 +-
 dom/xslt/xslt/txBufferingHandler.h            |   4 +-
 dom/xslt/xslt/txEXSLTFunctions.cpp            |   9 +-
 dom/xslt/xslt/txExecutionState.cpp            |  29 +-
 dom/xslt/xslt/txExecutionState.h              |   8 +-
 dom/xslt/xslt/txFormatNumberFunctionCall.cpp  |  23 +-
 dom/xslt/xslt/txInstructions.cpp              |  86 +--
 dom/xslt/xslt/txInstructions.h                |  94 +--
 dom/xslt/xslt/txKey.h                         |   7 +-
 dom/xslt/xslt/txKeyFunctionCall.cpp           |  15 +-
 dom/xslt/xslt/txMozillaStylesheetCompiler.cpp |  13 +-
 dom/xslt/xslt/txMozillaXMLOutput.cpp          |  31 +-
 dom/xslt/xslt/txMozillaXMLOutput.h            |   1 -
 dom/xslt/xslt/txMozillaXSLTProcessor.cpp      |  30 +-
 dom/xslt/xslt/txMozillaXSLTProcessor.h        |   3 +-
 dom/xslt/xslt/txNodeSorter.cpp                |   8 +-
 dom/xslt/xslt/txPatternParser.cpp             |  14 +-
 dom/xslt/xslt/txRtfHandler.cpp                |   6 +-
 dom/xslt/xslt/txRtfHandler.h                  |  10 +-
 dom/xslt/xslt/txStylesheet.cpp                | 137 ++---
 dom/xslt/xslt/txStylesheet.h                  |  26 +-
 dom/xslt/xslt/txStylesheetCompileHandlers.cpp | 549 ++++++++----------
 dom/xslt/xslt/txStylesheetCompiler.cpp        |  74 ++-
 dom/xslt/xslt/txStylesheetCompiler.h          |  12 +-
 dom/xslt/xslt/txToplevelItems.cpp             |  11 +-
 dom/xslt/xslt/txToplevelItems.h               |  15 +-
 dom/xslt/xslt/txUnknownHandler.cpp            |  18 +-
 dom/xslt/xslt/txXPathResultComparator.cpp     |  75 ++-
 dom/xslt/xslt/txXPathResultComparator.h       |  11 +-
 dom/xslt/xslt/txXSLTFunctions.h               |   2 +-
 dom/xslt/xslt/txXSLTNumber.cpp                |  26 +-
 dom/xslt/xslt/txXSLTPatterns.cpp              |  12 +-
 dom/xslt/xslt/txXSLTPatterns.h                |  10 +-
 dom/xul/XULDocument.cpp                       |   1 -
 268 files changed, 4743 insertions(+), 3119 deletions(-)
 rename dom/base/{nsStyleLinkElement.cpp => LinkStyle.cpp} (66%)
 create mode 100644 dom/base/LinkStyle.h
 delete mode 100644 dom/base/nsIStyleSheetLinkingElement.h
 delete mode 100644 dom/base/nsStyleLinkElement.h
 create mode 100644 dom/fetch/tests/crashtests/1664514.html
 create mode 100644 dom/fetch/tests/crashtests/url.url
 create mode 100644 dom/html/test/dialog/mochitest.ini
 create mode 100644 dom/html/test/dialog/test_cancelDialogByEscape.html
 create mode 100644 dom/html/test/dialog/test_dialog_cancel_events.html
 create mode 100644 dom/html/test/dialog/test_dialog_cancel_preventDefault.html
 create mode 100644 dom/html/test/dialog/test_dialog_keydown_preventDefault.html
 create mode 100644 dom/manifest/test/test_link_relList_supports_manifest.html
 create mode 100644 dom/script/ScriptKind.h
 create mode 100644 dom/security/test/csp/file_bug1505412.sjs
 create mode 100644 dom/security/test/csp/file_bug1505412_frame.html
 create mode 100644 dom/security/test/csp/file_bug1505412_frame.html^headers^
 create mode 100644 dom/security/test/csp/file_bug1505412_reporter.sjs
 create mode 100644 dom/security/test/csp/file_link_rel_preload.html
 create mode 100644 dom/security/test/csp/file_object_inherit.html
 create mode 100644 dom/security/test/csp/test_bug1505412.html
 create mode 100644 dom/security/test/csp/test_link_rel_preload.html
 create mode 100644 dom/security/test/csp/test_object_inherit.html
 create mode 100644 dom/xslt/crashtests/1589930.xml

diff --git a/dom/animation/KeyframeUtils.cpp b/dom/animation/KeyframeUtils.cpp
index 2fa823c171..4df501adb6 100644
--- a/dom/animation/KeyframeUtils.cpp
+++ b/dom/animation/KeyframeUtils.cpp
@@ -10,13 +10,13 @@
 #include "jsapi.h"             // For most JSAPI
 #include "mozilla/ComputedStyle.h"
 #include "mozilla/ErrorResult.h"
-#include "mozilla/Move.h"
+#include <utility>
 #include "mozilla/RangedArray.h"
-#include "mozilla/ServoBindingTypes.h"
 #include "mozilla/ServoBindings.h"
+#include "mozilla/ServoBindingTypes.h"
 #include "mozilla/ServoCSSParser.h"
-#include "mozilla/StaticPrefs_dom.h"
 #include "mozilla/StyleAnimationValue.h"
+#include "mozilla/StaticPrefs_dom.h"
 #include "mozilla/TimingParams.h"
 #include "mozilla/dom/BaseKeyframeTypesBinding.h"  // For FastBaseKeyframe etc.
 #include "mozilla/dom/BindingCallContext.h"
diff --git a/dom/base/AnonymousContent.cpp b/dom/base/AnonymousContent.cpp
index 8d3dad26f7..36f2566f87 100644
--- a/dom/base/AnonymousContent.cpp
+++ b/dom/base/AnonymousContent.cpp
@@ -6,6 +6,7 @@
 #include "mozilla/PresShell.h"
 #include "mozilla/dom/Document.h"
 #include "mozilla/dom/Element.h"
+#include "mozilla/dom/Event.h"
 #include "mozilla/dom/AnonymousContentBinding.h"
 #include "nsComputedDOMStyle.h"
 #include "nsCycleCollectionParticipant.h"
diff --git a/dom/base/AnonymousContent.h b/dom/base/AnonymousContent.h
index c1d0bb95d9..db571328b4 100644
--- a/dom/base/AnonymousContent.h
+++ b/dom/base/AnonymousContent.h
@@ -5,17 +5,24 @@
 #ifndef mozilla_dom_AnonymousContent_h
 #define mozilla_dom_AnonymousContent_h
 
-#include "mozilla/dom/Element.h"
-#include "mozilla/dom/Event.h"
 #include "nsCycleCollectionParticipant.h"
-#include "nsICSSDeclaration.h"
-#include "mozilla/dom/Document.h"
+
+class nsIPrincipal;
 
 namespace mozilla {
+class ErrorResult;
+
 namespace dom {
 
+class Animation;
+class DOMRect;
+class DOMString;
 class Element;
+class Event;
+template <typename T>
+class Sequence;
 class UnrestrictedDoubleOrAnonymousKeyframeAnimationOptions;
+class UnrestrictedDoubleOrKeyframeAnimationOptions;
 
 class AnonymousContent final {
  public:
diff --git a/dom/base/BodyConsumer.cpp b/dom/base/BodyConsumer.cpp
index 9d6739f08d..ae020242a4 100644
--- a/dom/base/BodyConsumer.cpp
+++ b/dom/base/BodyConsumer.cpp
@@ -5,6 +5,7 @@
 #include "BodyConsumer.h"
 
 #include "mozilla/dom/BlobBinding.h"
+#include "mozilla/dom/BlobImpl.h"
 #include "mozilla/dom/BlobURLProtocolHandler.h"
 #include "mozilla/dom/BodyUtil.h"
 #include "mozilla/dom/File.h"
@@ -19,6 +20,8 @@
 #include "mozilla/dom/WorkerRunnable.h"
 #include "mozilla/dom/WorkerScope.h"
 #include "mozilla/ipc/PBackgroundSharedTypes.h"
+#include "nsComponentManagerUtils.h"
+#include "nsIFile.h"
 #include "nsIThreadRetargetableRequest.h"
 #include "nsIStreamLoader.h"
 #include "nsNetUtil.h"
diff --git a/dom/base/BorrowedAttrInfo.cpp b/dom/base/BorrowedAttrInfo.cpp
index 029ca504f8..a4223d3dff 100644
--- a/dom/base/BorrowedAttrInfo.cpp
+++ b/dom/base/BorrowedAttrInfo.cpp
@@ -4,8 +4,7 @@
 
 #include "mozilla/dom/BorrowedAttrInfo.h"
 
-namespace mozilla {
-namespace dom {
+namespace mozilla::dom {
 
 BorrowedAttrInfo::BorrowedAttrInfo(const nsAttrName* aName,
                                    const nsAttrValue* aValue)
@@ -18,5 +17,4 @@ BorrowedAttrInfo::BorrowedAttrInfo(const BorrowedAttrInfo& aOther)
   MOZ_ASSERT_IF(mName, mValue);
 }
 
-}  // namespace dom
-}  // namespace mozilla
+}  // namespace mozilla::dom
diff --git a/dom/base/CustomElementRegistry.cpp b/dom/base/CustomElementRegistry.cpp
index 33ba81f533..ebb645960a 100644
--- a/dom/base/CustomElementRegistry.cpp
+++ b/dom/base/CustomElementRegistry.cpp
@@ -7,7 +7,9 @@
 #include "mozilla/AsyncEventDispatcher.h"
 #include "mozilla/CycleCollectedJSContext.h"
 #include "mozilla/dom/CustomElementRegistryBinding.h"
+#include "mozilla/dom/ElementBinding.h"
 #include "mozilla/dom/HTMLElementBinding.h"
+#include "mozilla/dom/PrimitiveConversions.h"
 #include "mozilla/dom/ShadowIncludingTreeIterator.h"
 #include "mozilla/dom/XULElementBinding.h"
 #include "mozilla/dom/Promise.h"
@@ -15,6 +17,7 @@
 #include "mozilla/dom/DocGroup.h"
 #include "mozilla/dom/CustomEvent.h"
 #include "mozilla/dom/ShadowRoot.h"
+#include "mozilla/AutoRestore.h"
 #include "nsHTMLTags.h"
 #include "jsapi.h"
 #include "js/ForOfIterator.h"  // JS::ForOfIterator
@@ -843,13 +846,15 @@ void CustomElementRegistry::Define(
   auto callbacksHolder = MakeUnique<LifecycleCallbacks>();
   nsTArray<RefPtr<nsAtom>> observedAttributes;
   AutoTArray<RefPtr<nsAtom>, 2> disabledFeatures;
+  bool formAssociated = false;
   bool disableInternals = false;
   bool disableShadow = false;
   {  // Set mIsCustomDefinitionRunning.
     /**
      * 9. Set this CustomElementRegistry's element definition is running flag.
      */
-    AutoSetRunningFlag as(this);
+    AutoRestore<bool> restoreRunning(mIsCustomDefinitionRunning);
+    mIsCustomDefinitionRunning = true;
 
     /**
      * 14.1. Let prototype be Get(constructor, "prototype"). Rethrow any
@@ -918,7 +923,7 @@ void CustomElementRegistry::Define(
      *       disabledFeaturesIterable to a sequence<DOMString>.
      *       Rethrow any exceptions from the conversion.
      */
-    if (StaticPrefs::dom_webcomponents_elementInternals_enabled()) {
+    if (StaticPrefs::dom_webcomponents_formAssociatedCustomElement_enabled()) {
       if (!JSObjectToAtomArray(aCx, constructor,
                                NS_LITERAL_STRING("disabledFeatures"),
                                disabledFeatures, aRv)) {
@@ -934,6 +939,24 @@ void CustomElementRegistry::Define(
       //        "shadow".
       disableShadow = disabledFeatures.Contains(
           static_cast<nsStaticAtom*>(nsGkAtoms::shadow));
+
+      // 14.11. Let formAssociatedValue be Get(constructor, "formAssociated").
+      //        Rethrow any exceptions.
+      JS::Rooted<JS::Value> formAssociatedValue(aCx);
+      if (!JS_GetProperty(aCx, constructor, "formAssociated",
+                          &formAssociatedValue)) {
+        aRv.NoteJSContextException(aCx);
+        return;
+      }
+
+      // 14.12. Set formAssociated to the result of converting
+      //        formAssociatedValue to a boolean. Rethrow any exceptions from
+      //        the conversion.
+      if (!ValueToPrimitive<bool, eDefault>(
+              aCx, formAssociatedValue, "formAssociated", &formAssociated)) {
+        aRv.NoteJSContextException(aCx);
+        return;
+      }
     }
   }  // Unset mIsCustomDefinitionRunning
 
@@ -956,7 +979,7 @@ void CustomElementRegistry::Define(
 
   RefPtr<CustomElementDefinition> definition = new CustomElementDefinition(
       nameAtom, localNameAtom, nameSpaceID, &aFunctionConstructor,
-      std::move(observedAttributes), std::move(callbacksHolder),
+      std::move(observedAttributes), std::move(callbacksHolder), formAssociated,
       disableInternals, disableShadow);
 
   CustomElementDefinition* def = definition.get();
@@ -981,7 +1004,7 @@ void CustomElementRegistry::Define(
   RefPtr<Promise> promise;
   mWhenDefinedPromiseMap.Remove(nameAtom, getter_AddRefs(promise));
   if (promise) {
-    promise->MaybeResolveWithUndefined();
+    promise->MaybeResolve(def->mConstructor);
   }
 
   // Dispatch a "customelementdefined" event for DevTools.
@@ -1075,8 +1098,9 @@ already_AddRefed<Promise> CustomElementRegistry::WhenDefined(
     return promise.forget();
   }
 
-  if (mCustomDefinitions.GetWeak(nameAtom)) {
-    promise->MaybeResolve(JS::UndefinedHandleValue);
+  if (CustomElementDefinition* definition =
+          mCustomDefinitions.GetWeak(nameAtom)) {
+    promise->MaybeResolve(definition->mConstructor);
     return promise.forget();
   }
 
@@ -1459,14 +1483,15 @@ CustomElementDefinition::CustomElementDefinition(
     nsAtom* aType, nsAtom* aLocalName, int32_t aNamespaceID,
     CustomElementConstructor* aConstructor,
     nsTArray<RefPtr<nsAtom>>&& aObservedAttributes,
-    UniquePtr<LifecycleCallbacks>&& aCallbacks, bool aDisableInternals,
-    bool aDisableShadow)
+    UniquePtr<LifecycleCallbacks>&& aCallbacks, bool aFormAssociated,
+    bool aDisableInternals, bool aDisableShadow)
     : mType(aType),
       mLocalName(aLocalName),
       mNamespaceID(aNamespaceID),
       mConstructor(aConstructor),
       mObservedAttributes(std::move(aObservedAttributes)),
       mCallbacks(std::move(aCallbacks)),
+      mFormAssociated(aFormAssociated),
       mDisableInternals(aDisableInternals),
       mDisableShadow(aDisableShadow) {}
 
diff --git a/dom/base/CustomElementRegistry.h b/dom/base/CustomElementRegistry.h
index cb946825a9..63ff9ae62f 100644
--- a/dom/base/CustomElementRegistry.h
+++ b/dom/base/CustomElementRegistry.h
@@ -139,7 +139,8 @@ struct CustomElementDefinition {
                           CustomElementConstructor* aConstructor,
                           nsTArray<RefPtr<nsAtom>>&& aObservedAttributes,
                           UniquePtr<LifecycleCallbacks>&& aCallbacks,
-                          bool aDisableInternals, bool aDisableShadow);
+                          bool aFormAssociated, bool aDisableInternals,
+                          bool aDisableShadow);
 
   // The type (name) for this custom element, for <button is="x-foo"> or <x-foo>
   // this would be x-foo.
@@ -160,6 +161,10 @@ struct CustomElementDefinition {
   // The lifecycle callbacks to call for this custom element.
   UniquePtr<LifecycleCallbacks> mCallbacks;
 
+  // If this is true, user agent treats elements associated to this custom
+  // element definition as form-associated custom elements.
+  bool mFormAssociated = false;
+
   // Determine whether to allow to attachInternals() for this custom element.
   bool mDisableInternals = false;
 
@@ -537,21 +542,6 @@ class CustomElementRegistry final : public nsISupports, public nsWrapperCache {
   bool mIsCustomDefinitionRunning;
 
  private:
-  class MOZ_RAII AutoSetRunningFlag final {
-   public:
-    explicit AutoSetRunningFlag(CustomElementRegistry* aRegistry)
-        : mRegistry(aRegistry) {
-      MOZ_ASSERT(!mRegistry->mIsCustomDefinitionRunning,
-                 "IsCustomDefinitionRunning flag should be initially false");
-      mRegistry->mIsCustomDefinitionRunning = true;
-    }
-
-    ~AutoSetRunningFlag() { mRegistry->mIsCustomDefinitionRunning = false; }
-
-   private:
-    CustomElementRegistry* mRegistry;
-  };
-
   int32_t InferNamespace(JSContext* aCx, JS::Handle<JSObject*> constructor);
 
  public:
diff --git a/dom/base/DOMMatrix.cpp b/dom/base/DOMMatrix.cpp
index c08d6fa079..ed2d2b1951 100644
--- a/dom/base/DOMMatrix.cpp
+++ b/dom/base/DOMMatrix.cpp
@@ -357,11 +357,12 @@ already_AddRefed<DOMMatrix> DOMMatrixReadOnly::FlipX() const {
   if (mMatrix3D) {
     gfx::Matrix4x4Double m;
     m._11 = -1;
-    retval->mMatrix3D = new gfx::Matrix4x4Double(m * *mMatrix3D);
+    retval->mMatrix3D = MakeUnique<gfx::Matrix4x4Double>(m * *mMatrix3D);
   } else {
     gfx::MatrixDouble m;
     m._11 = -1;
-    retval->mMatrix2D = new gfx::MatrixDouble(mMatrix2D ? m * *mMatrix2D : m);
+    retval->mMatrix2D =
+        MakeUnique<gfx::MatrixDouble>(mMatrix2D ? m * *mMatrix2D : m);
   }
 
   return retval.forget();
@@ -372,11 +373,12 @@ already_AddRefed<DOMMatrix> DOMMatrixReadOnly::FlipY() const {
   if (mMatrix3D) {
     gfx::Matrix4x4Double m;
     m._22 = -1;
-    retval->mMatrix3D = new gfx::Matrix4x4Double(m * *mMatrix3D);
+    retval->mMatrix3D = MakeUnique<gfx::Matrix4x4Double>(m * *mMatrix3D);
   } else {
     gfx::MatrixDouble m;
     m._22 = -1;
-    retval->mMatrix2D = new gfx::MatrixDouble(mMatrix2D ? m * *mMatrix2D : m);
+    retval->mMatrix2D =
+        MakeUnique<gfx::MatrixDouble>(mMatrix2D ? m * *mMatrix2D : m);
   }
 
   return retval.forget();
@@ -748,8 +750,8 @@ already_AddRefed<DOMMatrix> DOMMatrix::ReadStructuredClone(
 
 void DOMMatrixReadOnly::Ensure3DMatrix() {
   if (!mMatrix3D) {
-    mMatrix3D =
-        new gfx::Matrix4x4Double(gfx::Matrix4x4Double::From2D(*mMatrix2D));
+    mMatrix3D = MakeUnique<gfx::Matrix4x4Double>(
+        gfx::Matrix4x4Double::From2D(*mMatrix2D));
     mMatrix2D = nullptr;
   }
 }
@@ -964,7 +966,7 @@ DOMMatrix* DOMMatrix::InvertSelf() {
   } else if (!mMatrix2D->Invert()) {
     mMatrix2D = nullptr;
 
-    mMatrix3D = new gfx::Matrix4x4Double();
+    mMatrix3D = MakeUnique<gfx::Matrix4x4Double>();
     mMatrix3D->SetNAN();
   }
 
@@ -989,7 +991,7 @@ DOMMatrixReadOnly* DOMMatrixReadOnly::SetMatrixValue(
   if (!contains3dTransform) {
     mMatrix3D = nullptr;
     if (!mMatrix2D) {
-      mMatrix2D = new gfx::MatrixDouble();
+      mMatrix2D = MakeUnique<gfx::MatrixDouble>();
     }
 
     SetA(transform._11);
@@ -999,7 +1001,7 @@ DOMMatrixReadOnly* DOMMatrixReadOnly::SetMatrixValue(
     SetE(transform._41);
     SetF(transform._42);
   } else {
-    mMatrix3D = new gfx::Matrix4x4Double(transform);
+    mMatrix3D = MakeUnique<gfx::Matrix4x4Double>(transform);
     mMatrix2D = nullptr;
   }
 
diff --git a/dom/base/DOMMatrix.h b/dom/base/DOMMatrix.h
index a70b15451e..1ddfa80584 100644
--- a/dom/base/DOMMatrix.h
+++ b/dom/base/DOMMatrix.h
@@ -11,6 +11,7 @@
 #include "nsCycleCollectionParticipant.h"
 #include "mozilla/Attributes.h"
 #include "mozilla/ErrorResult.h"
+#include "mozilla/UniquePtr.h"
 #include "nsCOMPtr.h"
 #include "mozilla/dom/BindingDeclarations.h"
 #include "mozilla/dom/TypedArray.h"
@@ -37,20 +38,20 @@ class DOMMatrixReadOnly : public nsWrapperCache {
   DOMMatrixReadOnly(nsISupports* aParent, const DOMMatrixReadOnly& other)
       : mParent(aParent) {
     if (other.mMatrix2D) {
-      mMatrix2D = new gfx::MatrixDouble(*other.mMatrix2D);
+      mMatrix2D = MakeUnique<gfx::MatrixDouble>(*other.mMatrix2D);
     } else {
-      mMatrix3D = new gfx::Matrix4x4Double(*other.mMatrix3D);
+      mMatrix3D = MakeUnique<gfx::Matrix4x4Double>(*other.mMatrix3D);
     }
   }
 
   DOMMatrixReadOnly(nsISupports* aParent, const gfx::Matrix4x4& aMatrix)
       : mParent(aParent) {
-    mMatrix3D = new gfx::Matrix4x4Double(aMatrix);
+    mMatrix3D = MakeUnique<gfx::Matrix4x4Double>(aMatrix);
   }
 
   DOMMatrixReadOnly(nsISupports* aParent, const gfx::Matrix& aMatrix)
       : mParent(aParent) {
-    mMatrix2D = new gfx::MatrixDouble(aMatrix);
+    mMatrix2D = MakeUnique<gfx::MatrixDouble>(aMatrix);
   }
 
   NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING(DOMMatrixReadOnly)
@@ -218,15 +219,15 @@ class DOMMatrixReadOnly : public nsWrapperCache {
                             JSStructuredCloneWriter* aWriter) const;
   const gfx::MatrixDouble* GetInternal2D() const {
     if (Is2D()) {
-      return mMatrix2D;
+      return mMatrix2D.get();
     }
     return nullptr;
   }
 
  protected:
   nsCOMPtr<nsISupports> mParent;
-  nsAutoPtr<gfx::MatrixDouble> mMatrix2D;
-  nsAutoPtr<gfx::Matrix4x4Double> mMatrix3D;
+  UniquePtr<gfx::MatrixDouble> mMatrix2D;
+  UniquePtr<gfx::Matrix4x4Double> mMatrix3D;
 
   virtual ~DOMMatrixReadOnly() = default;
 
@@ -243,9 +244,9 @@ class DOMMatrixReadOnly : public nsWrapperCache {
 
   DOMMatrixReadOnly(nsISupports* aParent, bool is2D) : mParent(aParent) {
     if (is2D) {
-      mMatrix2D = new gfx::MatrixDouble();
+      mMatrix2D = MakeUnique<gfx::MatrixDouble>();
     } else {
-      mMatrix3D = new gfx::Matrix4x4Double();
+      mMatrix3D = MakeUnique<gfx::Matrix4x4Double>();
     }
   }
 
diff --git a/dom/base/Document.cpp b/dom/base/Document.cpp
index 0992f0bc61..c86b8c8af0 100644
--- a/dom/base/Document.cpp
+++ b/dom/base/Document.cpp
@@ -90,6 +90,7 @@
 #include "mozilla/dom/CSPDictionariesBinding.h"
 #include "mozilla/dom/DOMIntersectionObserver.h"
 #include "mozilla/dom/Element.h"
+#include "mozilla/dom/ElementBinding.h"
 #include "mozilla/dom/Event.h"
 #include "mozilla/dom/FeaturePolicy.h"
 #include "mozilla/dom/FeaturePolicyUtils.h"
@@ -97,6 +98,7 @@
 #include "mozilla/dom/HTMLAllCollection.h"
 #include "mozilla/dom/HTMLMetaElement.h"
 #include "mozilla/dom/HTMLSharedElement.h"
+#include "mozilla/dom/HTMLDialogElement.h"
 #include "mozilla/dom/MutationObservers.h"
 #include "mozilla/dom/Navigator.h"
 #include "mozilla/dom/Performance.h"
@@ -411,7 +413,7 @@ bool IdentifierMapEntry::HasNameElement() const {
 void IdentifierMapEntry::AddContentChangeCallback(
     Document::IDTargetObserver aCallback, void* aData, bool aForImage) {
   if (!mChangeCallbacks) {
-    mChangeCallbacks = new nsTHashtable<ChangeCallbackEntry>;
+    mChangeCallbacks = MakeUnique<nsTHashtable<ChangeCallbackEntry>>();
   }
 
   ChangeCallback cc = {aCallback, aData, aForImage};
@@ -1335,7 +1337,8 @@ Document::Document(const char* aContentType)
       mPendingInitialTranslation(false),
       mGeneration(0),
       mCachedTabSizeGeneration(0),
-      mInRDMPane(false) {
+      mInRDMPane(false),
+      mPreloadService(this) {
   MOZ_LOG(gDocumentLeakPRLog, LogLevel::Debug, ("DOCUMENT %p created", this));
 
   SetIsInDocument();
@@ -1757,9 +1760,6 @@ NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INTERNAL(Document)
     }
   }
 
-  if (tmp->mResizeObserverController) {
-    tmp->mResizeObserverController->Traverse(cb);
-  }
   for (size_t i = 0; i < tmp->mMetaViewports.Length(); i++) {
     NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mMetaViewports[i].mElement);
   }
@@ -1885,9 +1885,6 @@ NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(Document)
 
   tmp->mInUnlinkOrDeletion = false;
 
-  if (tmp->mResizeObserverController) {
-    tmp->mResizeObserverController->Unlink();
-  }
   tmp->mMetaViewports.Clear();
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mL10nProtoElements)
 NS_IMPL_CYCLE_COLLECTION_UNLINK_END
@@ -3330,8 +3327,10 @@ bool Document::DocumentSupportsL10n(JSContext* aCx, JSObject* aObject) {
   nsCOMPtr<nsIPrincipal> callerPrincipal =
       nsContentUtils::SubjectPrincipal(aCx);
   nsGlobalWindowInner* win = xpc::WindowOrNull(aObject);
-  return nsContentUtils::PrincipalAllowsL10n(
-      callerPrincipal, win ? win->GetDocumentURI() : nullptr);
+  bool allowed = false;
+  callerPrincipal->IsL10nAllowed(win ? win->GetDocumentURI() : nullptr,
+                                 &allowed);
+  return allowed;
 }
 
 void Document::LocalizationLinkAdded(Element* aLinkElement) {
@@ -3440,7 +3439,9 @@ void Document::InitialDocumentTranslationCompleted() {
 }
 
 bool Document::AllowsL10n() const {
-  return nsContentUtils::PrincipalAllowsL10n(NodePrincipal(), GetDocumentURI());
+  bool allowed = false;
+  NodePrincipal()->IsL10nAllowed(GetDocumentURI(), &allowed);
+  return allowed;
 }
 
 bool Document::IsWebAnimationsEnabled(JSContext* aCx, JSObject* /*unused*/) {
@@ -5211,7 +5212,7 @@ void Document::SetCookie(const nsAString& aCookie, ErrorResult& rv) {
     }
 
     NS_ConvertUTF16toUTF8 cookie(aCookie);
-    service->SetCookieString(codebaseURI, nullptr, cookie, channel);
+    service->SetCookieString(codebaseURI, cookie, channel);
   }
 }
 
@@ -10105,6 +10106,9 @@ void Document::Destroy() {
   // Manually break cycles via promise's global object pointer.
   mReadyForIdle = nullptr;
   mOrientationPendingPromise = nullptr;
+
+  // To break cycles.
+  mPreloadService.ClearAllPreloads();
 }
 
 void Document::RemovedFromDocShell() {
@@ -10930,16 +10934,9 @@ already_AddRefed<nsIURI> Document::ResolvePreloadImage(
   return uri.forget();
 }
 
-void Document::MaybePreLoadImage(nsIURI* uri, const nsAString& aCrossOriginAttr,
-                                 enum ReferrerPolicy aReferrerPolicy,
-                                 bool aIsImgSet) {
-  // Early exit if the img is already present in the img-cache
-  // which indicates that the "real" load has already started and
-  // that we shouldn't preload it.
-  if (nsContentUtils::IsImageInCache(uri, this)) {
-    return;
-  }
-
+void Document::PreLoadImage(nsIURI* aUri, const nsAString& aCrossOriginAttr,
+                            ReferrerPolicyEnum aReferrerPolicy, bool aIsImgSet,
+                            bool aLinkPreload) {
   nsLoadFlags loadFlags = nsIRequest::LOAD_NORMAL |
                           nsContentUtils::CORSModeToLoadImageFlags(
                               Element::StringToCORSMode(aCrossOriginAttr));
@@ -10951,19 +10948,48 @@ void Document::MaybePreLoadImage(nsIURI* uri, const nsAString& aCrossOriginAttr,
   nsCOMPtr<nsIReferrerInfo> referrerInfo =
       ReferrerInfo::CreateFromDocumentAndPolicyOverride(this, aReferrerPolicy);
 
-  // Image not in cache - trigger preload
   RefPtr<imgRequestProxy> request;
   nsresult rv = nsContentUtils::LoadImage(
-      uri, static_cast<nsINode*>(this), this, NodePrincipal(), 0, referrerInfo,
-      nullptr,  // no observer
-      loadFlags, NS_LITERAL_STRING("img"), getter_AddRefs(request), policyType);
+      aUri, static_cast<nsINode*>(this), this, NodePrincipal(), 0, referrerInfo,
+      nullptr /* no observer */, loadFlags,
+      aLinkPreload ? NS_LITERAL_STRING("link") : NS_LITERAL_STRING("img"),
+      getter_AddRefs(request), policyType, false /* urgent */, aLinkPreload);
 
   // Pin image-reference to avoid evicting it from the img-cache before
   // the "real" load occurs. Unpinned in DispatchContentLoadedEvents and
   // unlink
-  if (NS_SUCCEEDED(rv)) {
-    mPreloadingImages.Put(uri, std::move(request));
+  if (!aLinkPreload && NS_SUCCEEDED(rv)) {
+    mPreloadingImages.Put(aUri, std::move(request));
+  }
+}
+
+void Document::MaybePreLoadImage(nsIURI* aUri,
+                                 const nsAString& aCrossOriginAttr,
+                                 ReferrerPolicyEnum aReferrerPolicy,
+                                 bool aIsImgSet, bool aLinkPreload) {
+  if (aLinkPreload) {
+    // Check if the image was already preloaded in this document to avoid
+    // duplicate preloading.
+    PreloadHashKey key = PreloadHashKey::CreateAsImage(
+        aUri, NodePrincipal(), dom::Element::StringToCORSMode(aCrossOriginAttr),
+        aReferrerPolicy);
+    if (!mPreloadService.PreloadExists(&key)) {
+      PreLoadImage(aUri, aCrossOriginAttr, aReferrerPolicy, aIsImgSet,
+                   aLinkPreload);
+    }
+    return;
+  }
+
+  // Early exit if the img is already present in the img-cache
+  // which indicates that the "real" load has already started and
+  // that we shouldn't preload it.
+  if (nsContentUtils::IsImageInCache(aUri, this)) {
+    return;
   }
+
+  // Image not in cache - trigger preload
+  PreLoadImage(aUri, aCrossOriginAttr, aReferrerPolicy, aIsImgSet,
+               aLinkPreload);
 }
 
 void Document::MaybePreconnect(nsIURI* aOrigURI, mozilla::CORSMode aCORSMode) {
@@ -11071,18 +11097,20 @@ NS_IMPL_ISUPPORTS(StubCSSLoaderObserver, nsICSSLoaderObserver)
 void Document::PreloadStyle(nsIURI* uri, const Encoding* aEncoding,
                             const nsAString& aCrossOriginAttr,
                             const enum ReferrerPolicy aReferrerPolicy,
-                            const nsAString& aIntegrity) {
+                            const nsAString& aIntegrity, bool aIsLinkPreload) {
   // The CSSLoader will retain this object after we return.
   nsCOMPtr<nsICSSLoaderObserver> obs = new StubCSSLoaderObserver();
 
   nsCOMPtr<nsIReferrerInfo> referrerInfo =
       ReferrerInfo::CreateFromDocumentAndPolicyOverride(this, aReferrerPolicy);
 
+  auto preloadType = aIsLinkPreload ? css::Loader::IsPreload::FromLink
+                                    : css::Loader::IsPreload::FromParser;
+
   // Charset names are always ASCII.
   Unused << CSSLoader()->LoadSheet(
-      uri, css::Loader::IsPreload::Yes, NodePrincipal(), aEncoding,
-      referrerInfo, obs, Element::StringToCORSMode(aCrossOriginAttr),
-      aIntegrity);
+      uri, preloadType, aEncoding, referrerInfo, obs,
+      Element::StringToCORSMode(aCrossOriginAttr), aIntegrity);
 }
 
 RefPtr<StyleSheet> Document::LoadChromeSheetSync(nsIURI* uri) {
@@ -11322,6 +11350,13 @@ class nsAutoFocusEvent : public Runnable {
       return NS_OK;
     }
 
+    if (Document* doc = mTopWindow->GetExtantDoc()) {
+      if (doc->IsAutoFocusFired()) {
+        return NS_OK;
+      }
+      doc->SetAutoFocusFired();
+    }
+
     // Don't steal focus from the user.
     if (mTopWindow->GetFocusedElement()) {
       return NS_OK;
@@ -11354,6 +11389,10 @@ void Document::SetAutoFocusElement(Element* aAutoFocusElement) {
   TriggerAutoFocus();
 }
 
+void Document::SetAutoFocusFired() { mAutoFocusFired = true; }
+
+bool Document::IsAutoFocusFired() { return mAutoFocusFired; }
+
 void Document::TriggerAutoFocus() {
   if (mAutoFocusFired) {
     return;
@@ -11367,8 +11406,6 @@ void Document::TriggerAutoFocus() {
 
   nsCOMPtr<Element> autoFocusElement = do_QueryReferent(mAutoFocusElement);
   if (autoFocusElement && autoFocusElement->OwnerDoc() == this) {
-    mAutoFocusFired = true;
-
     nsCOMPtr<nsPIDOMWindowOuter> topWindow =
         FindTopWindowForElement(autoFocusElement);
     if (!topWindow) {
@@ -11481,7 +11518,7 @@ void Document::ScrollToRef() {
 
 void Document::RegisterActivityObserver(nsISupports* aSupports) {
   if (!mActivityObservers) {
-    mActivityObservers = new nsTHashtable<nsPtrHashKey<nsISupports>>();
+    mActivityObservers = MakeUnique<nsTHashtable<nsPtrHashKey<nsISupports>>>();
   }
   mActivityObservers->PutEntry(aSupports);
 }
@@ -12524,6 +12561,18 @@ void Document::SetFullscreenRoot(Document* aRoot) {
   mFullscreenRoot = do_GetWeakReference(aRoot);
 }
 
+void Document::TryCancelDialog() {
+  // Check if the document is blocked by modal dialog
+  for (const nsWeakPtr& weakPtr : Reversed(mTopLayer)) {
+    nsCOMPtr<Element> element(do_QueryReferent(weakPtr));
+    if (HTMLDialogElement* dialog =
+            HTMLDialogElement::FromNodeOrNull(element)) {
+      dialog->QueueCancelDialog();
+      break;
+    }
+  }
+}
+
 already_AddRefed<Promise> Document::ExitFullscreen(ErrorResult& aRv) {
   UniquePtr<FullscreenExit> exit = FullscreenExit::Create(this, aRv);
   RefPtr<Promise> promise = exit->GetPromise();
diff --git a/dom/base/Document.h b/dom/base/Document.h
index ffb9bc7d27..cf24e0808a 100644
--- a/dom/base/Document.h
+++ b/dom/base/Document.h
@@ -9,7 +9,6 @@
 #include "mozilla/FlushType.h"    // for enum
 #include "mozilla/MozPromise.h"   // for MozPromise
 #include "mozilla/FunctionRef.h"  // for FunctionRef
-#include "nsAutoPtr.h"            // for member
 #include "nsCOMArray.h"           // for member
 #include "nsCompatibility.h"      // for member
 #include "nsCOMPtr.h"             // for member
@@ -56,6 +55,7 @@
 #include "mozilla/HashTable.h"
 #include "mozilla/LinkedList.h"
 #include "mozilla/NotNull.h"
+#include "mozilla/PreloadService.h"
 #include "mozilla/SegmentedVector.h"
 #include "mozilla/TimeStamp.h"
 #include "mozilla/UniquePtr.h"
@@ -1700,6 +1700,8 @@ class Document : public nsINode,
 
   void SetKeyPressEventModel(uint16_t aKeyPressEventModel);
 
+  PreloadService& Preloads() { return mPreloadService; }
+
  protected:
   friend class nsUnblockOnloadEvent;
 
@@ -2088,6 +2090,9 @@ class Document : public nsINode,
   // flag.
   bool SetFullscreenElement(Element* aElement);
 
+  // Cancel the dialog element if the document is blocked by the dialog
+  void TryCancelDialog();
+
   /**
    * Called when a frame in a child process has entered fullscreen or when a
    * fullscreen frame in a child process changes to another origin.
@@ -3082,7 +3087,11 @@ class Document : public nsINode,
    * when this image is for loading <picture> or <img srcset> images.
    */
   void MaybePreLoadImage(nsIURI* uri, const nsAString& aCrossOriginAttr,
-                         ReferrerPolicyEnum aReferrerPolicy, bool aIsImgSet);
+                         ReferrerPolicyEnum aReferrerPolicy, bool aIsImgSet,
+                         bool aLinkPreload);
+  void PreLoadImage(nsIURI* uri, const nsAString& aCrossOriginAttr,
+                    ReferrerPolicyEnum aReferrerPolicy, bool aIsImgSet,
+                    bool aLinkPreload);
 
   /**
    * Called by images to forget an image preload when they start doing
@@ -3097,7 +3106,7 @@ class Document : public nsINode,
   void PreloadStyle(nsIURI* aURI, const Encoding* aEncoding,
                     const nsAString& aCrossOriginAttr,
                     ReferrerPolicyEnum aReferrerPolicy,
-                    const nsAString& aIntegrity);
+                    const nsAString& aIntegrity, bool aIsLinkPreload);
 
   /**
    * Called by the chrome registry to load style sheets.
@@ -3175,6 +3184,8 @@ class Document : public nsINode,
 
   void SetAutoFocusElement(Element* aAutoFocusElement);
   void TriggerAutoFocus();
+  void SetAutoFocusFired();
+  bool IsAutoFocusFired();
 
   void SetScrollToRef(nsIURI* aDocumentURI);
   MOZ_CAN_RUN_SCRIPT void ScrollToRef();
@@ -4405,7 +4416,7 @@ class Document : public nsINode,
   //
   // These are non-owning pointers, the elements are responsible for removing
   // themselves when they go away.
-  nsAutoPtr<nsTHashtable<nsPtrHashKey<nsISupports>>> mActivityObservers;
+  UniquePtr<nsTHashtable<nsPtrHashKey<nsISupports>>> mActivityObservers;
 
   // A hashtable of styled links keyed by address pointer.
   nsTHashtable<nsPtrHashKey<Link>> mStyledLinks;
@@ -5184,6 +5195,9 @@ class Document : public nsINode,
   // The principal to use for the content blocking allow list.
   nsCOMPtr<nsIPrincipal> mContentBlockingAllowListPrincipal;
 
+  // Scope preloads per document.  This is used by speculative loading as well.
+  PreloadService mPreloadService;
+
  public:
   // Needs to be public because the bindings code pokes at it.
   JS::ExpandoAndGeneration mExpandoAndGeneration;
diff --git a/dom/base/Element.cpp b/dom/base/Element.cpp
index 34fd2b0275..c04f241ec0 100644
--- a/dom/base/Element.cpp
+++ b/dom/base/Element.cpp
@@ -1171,7 +1171,8 @@ bool Element::CanAttachShadowDOM() const {
   // It will always have CustomElementData when the element is a valid custom
   // element or has is value.
   CustomElementData* ceData = GetCustomElementData();
-  if (StaticPrefs::dom_webcomponents_elementInternals_enabled() && ceData) {
+  if (StaticPrefs::dom_webcomponents_formAssociatedCustomElement_enabled() &&
+      ceData) {
     CustomElementDefinition* definition = ceData->GetCustomElementDefinition();
     // If the definition is null, the element possible hasn't yet upgraded.
     // Fallback to use LookupCustomElementDefinition to find its definition.
diff --git a/dom/base/Element.h b/dom/base/Element.h
index e7627c8acf..9df4ee0838 100644
--- a/dom/base/Element.h
+++ b/dom/base/Element.h
@@ -18,38 +18,29 @@
 #include "nsContentUtils.h"
 #include "nsDOMAttributeMap.h"
 #include "nsStyleConsts.h"
-#include "nsINodeList.h"
 #include "nsIScrollableFrame.h"
+#include "nsRect.h"
 #include "Units.h"
 #include "mozilla/Attributes.h"
 #include "mozilla/CORSMode.h"
-#include "mozilla/EventForwards.h"
 #include "mozilla/EventStates.h"
 #include "mozilla/FlushType.h"
 #include "mozilla/PseudoStyleType.h"
 #include "mozilla/RustCell.h"
 #include "mozilla/SMILAttr.h"
 #include "mozilla/UniquePtr.h"
-#include "mozilla/dom/Attr.h"
-#include "mozilla/dom/BindingDeclarations.h"
 #include "mozilla/dom/DirectionalityUtils.h"
 #include "mozilla/dom/FragmentOrElement.h"
-#include "mozilla/dom/DOMRect.h"
-#include "mozilla/dom/DOMTokenListSupportedTokens.h"
-#include "mozilla/dom/ElementBinding.h"
-#include "mozilla/dom/Nullable.h"
 #include "mozilla/dom/PointerEventHandler.h"
-#include "mozilla/dom/WindowBinding.h"
+#include "mozilla/dom/ShadowRootBinding.h"
 
 class mozAutoDocUpdate;
 class nsIFrame;
 class nsIMozBrowserFrame;
 class nsIURI;
-class nsIScrollableFrame;
 class nsAttrValueOrString;
 class nsContentList;
 class nsDOMTokenList;
-struct nsRect;
 class nsFocusManager;
 class nsGlobalWindowInner;
 class nsGlobalWindowOuter;
@@ -81,6 +72,9 @@ namespace dom {
 struct GetAnimationsOptions;
 struct ScrollIntoViewOptions;
 struct ScrollToOptions;
+struct FocusOptions;
+struct ShadowRootInit;
+class BooleanOrScrollIntoViewOptions;
 class DOMIntersectionObserver;
 class DOMMatrixReadOnly;
 class Element;
diff --git a/dom/base/EventSource.cpp b/dom/base/EventSource.cpp
index 5837997ec8..8d5c181977 100644
--- a/dom/base/EventSource.cpp
+++ b/dom/base/EventSource.cpp
@@ -17,7 +17,6 @@
 #include "mozilla/dom/WorkerRunnable.h"
 #include "mozilla/dom/WorkerScope.h"
 #include "mozilla/UniquePtrExtensions.h"
-#include "nsAutoPtr.h"
 #include "nsIThreadRetargetableStreamListener.h"
 #include "nsNetUtil.h"
 #include "nsIAuthPrompt.h"
diff --git a/dom/base/IdentifierMapEntry.h b/dom/base/IdentifierMapEntry.h
index bab2361e13..27525ebaa8 100644
--- a/dom/base/IdentifierMapEntry.h
+++ b/dom/base/IdentifierMapEntry.h
@@ -9,15 +9,14 @@
 #ifndef mozilla_IdentifierMapEntry_h
 #define mozilla_IdentifierMapEntry_h
 
-#include "PLDHashTable.h"
+#include <utility>
 
+#include "PLDHashTable.h"
 #include "mozilla/MemoryReporting.h"
-#include "mozilla/Move.h"
+#include "mozilla/UniquePtr.h"
 #include "mozilla/dom/TreeOrderedArray.h"
-
-#include "nsAutoPtr.h"
-#include "nsCOMPtr.h"
 #include "nsAtom.h"
+#include "nsCOMPtr.h"
 #include "nsHashKeys.h"
 #include "nsTArray.h"
 #include "nsTHashtable.h"
@@ -221,7 +220,7 @@ class IdentifierMapEntry : public PLDHashEntryHdr {
   OwningAtomOrString mKey;
   dom::TreeOrderedArray<Element> mIdContentList;
   RefPtr<nsBaseContentList> mNameContentList;
-  nsAutoPtr<nsTHashtable<ChangeCallbackEntry> > mChangeCallbacks;
+  UniquePtr<nsTHashtable<ChangeCallbackEntry> > mChangeCallbacks;
   RefPtr<Element> mImageElement;
 };
 
diff --git a/dom/base/ImageEncoder.cpp b/dom/base/ImageEncoder.cpp
index 8bfc045776..4c40a3a8e2 100644
--- a/dom/base/ImageEncoder.cpp
+++ b/dom/base/ImageEncoder.cpp
@@ -34,9 +34,7 @@ class SurfaceHelper : public Runnable {
   // It retrieves a SourceSurface reference and convert color format on main
   // thread and passes DataSourceSurface to caller thread.
   NS_IMETHOD Run() override {
-    // It guarantees the reference will be released on main thread.
-    nsCountedRef<nsMainThreadSourceSurfaceRef> surface;
-    surface.own(mImage->GetAsSourceSurface().take());
+    RefPtr<gfx::SourceSurface> surface = mImage->GetAsSourceSurface();
 
     if (surface->GetFormat() == gfx::SurfaceFormat::B8G8R8A8) {
       mDataSourceSurface = surface->GetDataSurface();
@@ -44,6 +42,9 @@ class SurfaceHelper : public Runnable {
       mDataSourceSurface = gfxUtils::CopySurfaceToDataSourceSurfaceWithFormat(
           surface, gfx::SurfaceFormat::B8G8R8A8);
     }
+
+    // It guarantees the reference will be released on main thread.
+    NS_ReleaseOnMainThreadSystemGroup("SurfaceHelper::surface", surface.forget());
     return NS_OK;
   }
 
diff --git a/dom/base/Link.cpp b/dom/base/Link.cpp
index e2604bf36f..db05f60c88 100644
--- a/dom/base/Link.cpp
+++ b/dom/base/Link.cpp
@@ -7,16 +7,10 @@
 #include "mozilla/EventStates.h"
 #include "mozilla/MemoryReporting.h"
 #include "mozilla/dom/Element.h"
-#if defined(MOZ_PLACES)
-#  include "mozilla/places/History.h"
-#else
-#  include "mozilla/IHistory.h"
-#endif
+#include "mozilla/IHistory.h"
 #include "nsIURL.h"
 #include "nsIURIMutator.h"
 #include "nsISizeOf.h"
-#include "nsIPrefetchService.h"
-#include "nsStyleLinkElement.h"
 
 #include "nsEscape.h"
 #include "nsGkAtoms.h"
@@ -31,10 +25,6 @@
 namespace mozilla {
 namespace dom {
 
-#if defined(MOZ_PLACES)
-using places::History;
-#endif
-
 Link::Link(Element* aElement)
     : mElement(aElement),
       mLinkState(eLinkState_NotLink),
@@ -133,14 +123,7 @@ EventStates Link::LinkState() const {
     // Make sure the href attribute has a valid link (bug 23209).
     // If we have a good href, register with History if available.
     if (mHistory && hrefURI) {
-#ifdef ANDROID
-      nsCOMPtr<IHistory> history = services::GetHistoryService();
-#elif defined(MOZ_PLACES)
-      History* history = History::GetService();
-#else
-      nsCOMPtr<IHistory> history;
-#endif
-      if (history) {
+      if (nsCOMPtr<IHistory> history = services::GetHistoryService()) {
         nsresult rv = history->RegisterVisitedCallback(hrefURI, self);
         if (NS_SUCCEEDED(rv)) {
           self->mRegistered = true;
@@ -555,14 +538,7 @@ void Link::UnregisterFromHistory() {
 
   // And tell History to stop tracking us.
   if (mHistory && mCachedURI) {
-#ifdef ANDROID
-    nsCOMPtr<IHistory> history = services::GetHistoryService();
-#elif defined(MOZ_PLACES)
-    History* history = History::GetService();
-#else
-    nsCOMPtr<IHistory> history;
-#endif
-    if (history) {
+    if (nsCOMPtr<IHistory> history = services::GetHistoryService()) {
       nsresult rv = history->UnregisterVisitedCallback(mCachedURI, this);
       NS_ASSERTION(NS_SUCCEEDED(rv),
                    "This should only fail if we misuse the API!");
diff --git a/dom/base/nsStyleLinkElement.cpp b/dom/base/LinkStyle.cpp
similarity index 66%
rename from dom/base/nsStyleLinkElement.cpp
rename to dom/base/LinkStyle.cpp
index fee712167f..106de1f656 100644
--- a/dom/base/nsStyleLinkElement.cpp
+++ b/dom/base/LinkStyle.cpp
@@ -8,7 +8,7 @@
  * stylesheets (<style>, <link>, processing instructions, etc).
  */
 
-#include "nsStyleLinkElement.h"
+#include "mozilla/dom/LinkStyle.h"
 
 #include "mozilla/StyleSheet.h"
 #include "mozilla/StyleSheetInlines.h"
@@ -29,10 +29,10 @@
 #include "nsStyleUtil.h"
 #include "nsQueryObject.h"
 
-using namespace mozilla;
-using namespace mozilla::dom;
+namespace mozilla {
+namespace dom {
 
-nsStyleLinkElement::SheetInfo::SheetInfo(
+LinkStyle::SheetInfo::SheetInfo(
     const Document& aDocument, nsIContent* aContent,
     already_AddRefed<nsIURI> aURI,
     already_AddRefed<nsIPrincipal> aTriggeringPrincipal,
@@ -60,21 +60,15 @@ nsStyleLinkElement::SheetInfo::SheetInfo(
              "Integrity only applies to <link>");
 }
 
-nsStyleLinkElement::SheetInfo::~SheetInfo() = default;
+LinkStyle::SheetInfo::~SheetInfo() = default;
 
-nsStyleLinkElement::nsStyleLinkElement()
-    : mDontLoadStyle(false),
-      mUpdatesEnabled(true),
-      mLineNumber(1),
-      mColumnNumber(1) {}
+LinkStyle::LinkStyle()
+    : mUpdatesEnabled(true), mLineNumber(1), mColumnNumber(1) {}
 
-nsStyleLinkElement::~nsStyleLinkElement() {
-  nsStyleLinkElement::SetStyleSheet(nullptr);
-}
+LinkStyle::~LinkStyle() { LinkStyle::SetStyleSheet(nullptr); }
 
-void nsStyleLinkElement::GetTitleAndMediaForElement(const Element& aSelf,
-                                                    nsString& aTitle,
-                                                    nsString& aMedia) {
+void LinkStyle::GetTitleAndMediaForElement(const Element& aSelf,
+                                           nsString& aTitle, nsString& aMedia) {
   // Only honor title as stylesheet name for elements in the document (that is,
   // ignore for Shadow DOM), per [1] and [2]. See [3].
   //
@@ -95,8 +89,7 @@ void nsStyleLinkElement::GetTitleAndMediaForElement(const Element& aSelf,
   nsContentUtils::ASCIIToLower(aMedia);
 }
 
-bool nsStyleLinkElement::IsCSSMimeTypeAttributeForStyleElement(
-    const Element& aSelf) {
+bool LinkStyle::IsCSSMimeTypeAttributeForStyleElement(const Element& aSelf) {
   // Per
   // https://html.spec.whatwg.org/multipage/semantics.html#the-style-element:update-a-style-block
   // step 4, for style elements we should only accept empty and "text/css" type
@@ -106,85 +99,47 @@ bool nsStyleLinkElement::IsCSSMimeTypeAttributeForStyleElement(
   return type.IsEmpty() || type.LowerCaseEqualsLiteral("text/css");
 }
 
-void nsStyleLinkElement::Unlink() {
-  nsStyleLinkElement::SetStyleSheet(nullptr);
-}
+void LinkStyle::Unlink() { LinkStyle::SetStyleSheet(nullptr); }
 
-void nsStyleLinkElement::Traverse(nsCycleCollectionTraversalCallback& cb) {
-  nsStyleLinkElement* tmp = this;
+void LinkStyle::Traverse(nsCycleCollectionTraversalCallback& cb) {
+  LinkStyle* tmp = this;
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mStyleSheet);
 }
 
-void nsStyleLinkElement::SetStyleSheet(StyleSheet* aStyleSheet) {
+void LinkStyle::SetStyleSheet(StyleSheet* aStyleSheet) {
   if (mStyleSheet) {
     mStyleSheet->SetOwningNode(nullptr);
   }
 
   mStyleSheet = aStyleSheet;
   if (mStyleSheet) {
-    nsCOMPtr<nsINode> node = do_QueryObject(this);
-    if (node) {
-      mStyleSheet->SetOwningNode(node);
-    }
+    mStyleSheet->SetOwningNode(&AsContent());
   }
 }
 
-void nsStyleLinkElement::InitStyleLinkElement(bool aDontLoadStyle) {
-  mDontLoadStyle = aDontLoadStyle;
-}
-
-void nsStyleLinkElement::SetEnableUpdates(bool aEnableUpdates) {
-  mUpdatesEnabled = aEnableUpdates;
-}
-
-void nsStyleLinkElement::GetCharset(nsAString& aCharset) {
-  aCharset.Truncate();
-}
-
-/* virtual */
-void nsStyleLinkElement::OverrideBaseURI(nsIURI* aNewBaseURI) {
-  MOZ_ASSERT_UNREACHABLE(
-      "Base URI can't be overriden in this implementation "
-      "of nsIStyleSheetLinkingElement.");
-}
-
-/* virtual */
-void nsStyleLinkElement::SetLineNumber(uint32_t aLineNumber) {
-  mLineNumber = aLineNumber;
-}
-
-/* virtual */
-uint32_t nsStyleLinkElement::GetLineNumber() { return mLineNumber; }
-
-/* virtual */
-void nsStyleLinkElement::SetColumnNumber(uint32_t aColumnNumber) {
-  mColumnNumber = aColumnNumber;
-}
-
-/* virtual */
-uint32_t nsStyleLinkElement::GetColumnNumber() { return mColumnNumber; }
+void LinkStyle::GetCharset(nsAString& aCharset) { aCharset.Truncate(); }
 
 static uint32_t ToLinkMask(const nsAString& aLink) {
   // Keep this in sync with sRelValues in HTMLLinkElement.cpp
   if (aLink.EqualsLiteral("prefetch"))
-    return nsStyleLinkElement::ePREFETCH;
+    return LinkStyle::ePREFETCH;
   else if (aLink.EqualsLiteral("dns-prefetch"))
-    return nsStyleLinkElement::eDNS_PREFETCH;
+    return LinkStyle::eDNS_PREFETCH;
   else if (aLink.EqualsLiteral("stylesheet"))
-    return nsStyleLinkElement::eSTYLESHEET;
+    return LinkStyle::eSTYLESHEET;
   else if (aLink.EqualsLiteral("next"))
-    return nsStyleLinkElement::eNEXT;
+    return LinkStyle::eNEXT;
   else if (aLink.EqualsLiteral("alternate"))
-    return nsStyleLinkElement::eALTERNATE;
+    return LinkStyle::eALTERNATE;
   else if (aLink.EqualsLiteral("preconnect"))
-    return nsStyleLinkElement::ePRECONNECT;
+    return LinkStyle::ePRECONNECT;
   else if (aLink.EqualsLiteral("preload"))
-    return nsStyleLinkElement::ePRELOAD;
+    return LinkStyle::ePRELOAD;
   else
     return 0;
 }
 
-uint32_t nsStyleLinkElement::ParseLinkTypes(const nsAString& aTypes) {
+uint32_t LinkStyle::ParseLinkTypes(const nsAString& aTypes) {
   uint32_t linkMask = 0;
   nsAString::const_iterator start, done;
   aTypes.BeginReading(start);
@@ -217,29 +172,23 @@ uint32_t nsStyleLinkElement::ParseLinkTypes(const nsAString& aTypes) {
   return linkMask;
 }
 
-Result<nsStyleLinkElement::Update, nsresult>
-nsStyleLinkElement::UpdateStyleSheet(nsICSSLoaderObserver* aObserver) {
+Result<LinkStyle::Update, nsresult> LinkStyle::UpdateStyleSheet(
+    nsICSSLoaderObserver* aObserver) {
   return DoUpdateStyleSheet(nullptr, nullptr, aObserver, ForceUpdate::No);
 }
 
-Result<nsStyleLinkElement::Update, nsresult>
-nsStyleLinkElement::UpdateStyleSheetInternal(Document* aOldDocument,
-                                             ShadowRoot* aOldShadowRoot,
-                                             ForceUpdate aForceUpdate) {
+Result<LinkStyle::Update, nsresult> LinkStyle::UpdateStyleSheetInternal(
+    Document* aOldDocument, ShadowRoot* aOldShadowRoot,
+    ForceUpdate aForceUpdate) {
   return DoUpdateStyleSheet(aOldDocument, aOldShadowRoot, nullptr,
                             aForceUpdate);
 }
 
-Result<nsStyleLinkElement::Update, nsresult>
-nsStyleLinkElement::DoUpdateStyleSheet(Document* aOldDocument,
-                                       ShadowRoot* aOldShadowRoot,
-                                       nsICSSLoaderObserver* aObserver,
-                                       ForceUpdate aForceUpdate) {
-  nsCOMPtr<nsIContent> thisContent = do_QueryInterface(this);
-  // All instances of nsStyleLinkElement should implement nsIContent.
-  MOZ_ASSERT(thisContent);
-
-  if (thisContent->IsInSVGUseShadowTree()) {
+Result<LinkStyle::Update, nsresult> LinkStyle::DoUpdateStyleSheet(
+    Document* aOldDocument, ShadowRoot* aOldShadowRoot,
+    nsICSSLoaderObserver* aObserver, ForceUpdate aForceUpdate) {
+  nsIContent& thisContent = AsContent();
+  if (thisContent.IsInSVGUseShadowTree()) {
     // Stylesheets in <use>-cloned subtrees are disabled until we figure out
     // how they should behave.
     return Update{};
@@ -264,7 +213,7 @@ nsStyleLinkElement::DoUpdateStyleSheet(Document* aOldDocument,
     SetStyleSheet(nullptr);
   }
 
-  Document* doc = thisContent->GetComposedDoc();
+  Document* doc = thisContent.GetComposedDoc();
 
   // Loader could be null during unlink, see bug 1425866.
   if (!doc || !doc->CSSLoader() || !doc->CSSLoader()->GetEnabled()) {
@@ -272,7 +221,7 @@ nsStyleLinkElement::DoUpdateStyleSheet(Document* aOldDocument,
   }
 
   // When static documents are created, stylesheets are cloned manually.
-  if (mDontLoadStyle || !mUpdatesEnabled || doc->IsStaticDocument()) {
+  if (!mUpdatesEnabled || doc->IsStaticDocument()) {
     return Update{};
   }
 
@@ -289,8 +238,8 @@ nsStyleLinkElement::DoUpdateStyleSheet(Document* aOldDocument,
   }
 
   if (mStyleSheet) {
-    if (thisContent->IsInShadowTree()) {
-      ShadowRoot* containingShadow = thisContent->GetContainingShadow();
+    if (thisContent.IsInShadowTree()) {
+      ShadowRoot* containingShadow = thisContent.GetContainingShadow();
       // Could be null only during unlink.
       if (MOZ_LIKELY(containingShadow)) {
         containingShadow->RemoveStyleSheet(*mStyleSheet);
@@ -299,7 +248,7 @@ nsStyleLinkElement::DoUpdateStyleSheet(Document* aOldDocument,
       doc->RemoveStyleSheet(*mStyleSheet);
     }
 
-    nsStyleLinkElement::SetStyleSheet(nullptr);
+    LinkStyle::SetStyleSheet(nullptr);
   }
 
   if (!info) {
@@ -313,17 +262,17 @@ nsStyleLinkElement::DoUpdateStyleSheet(Document* aOldDocument,
 
   if (info->mIsInline) {
     nsAutoString text;
-    if (!nsContentUtils::GetNodeTextContent(thisContent, false, text,
+    if (!nsContentUtils::GetNodeTextContent(&thisContent, false, text,
                                             fallible)) {
       return Err(NS_ERROR_OUT_OF_MEMORY);
     }
 
-    MOZ_ASSERT(thisContent->NodeInfo()->NameAtom() != nsGkAtoms::link,
+    MOZ_ASSERT(thisContent.NodeInfo()->NameAtom() != nsGkAtoms::link,
                "<link> is not 'inline', and needs different CSP checks");
-    MOZ_ASSERT(thisContent->IsElement());
+    MOZ_ASSERT(thisContent.IsElement());
     nsresult rv = NS_OK;
     if (!nsStyleUtil::CSPAllowsInlineStyle(
-            thisContent->AsElement(), doc, info->mTriggeringPrincipal,
+            thisContent.AsElement(), doc, info->mTriggeringPrincipal,
             mLineNumber, mColumnNumber, text, &rv)) {
       if (NS_FAILED(rv)) {
         return Err(rv);
@@ -335,13 +284,13 @@ nsStyleLinkElement::DoUpdateStyleSheet(Document* aOldDocument,
     return doc->CSSLoader()->LoadInlineStyle(*info, text, mLineNumber,
                                              aObserver);
   }
-  if (thisContent->IsElement()) {
+  if (thisContent.IsElement()) {
     nsAutoString integrity;
-    thisContent->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::integrity,
-                                      integrity);
+    thisContent.AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::integrity,
+                                     integrity);
     if (!integrity.IsEmpty()) {
       MOZ_LOG(SRILogHelper::GetSriLog(), mozilla::LogLevel::Debug,
-              ("nsStyleLinkElement::DoUpdateStyleSheet, integrity=%s",
+              ("LinkStyle::DoUpdateStyleSheet, integrity=%s",
                NS_ConvertUTF16toUTF8(integrity).get()));
     }
   }
@@ -354,3 +303,6 @@ nsStyleLinkElement::DoUpdateStyleSheet(Document* aOldDocument,
   }
   return resultOrError;
 }
+
+}  // namespace dom
+}  // namespace mozilla
diff --git a/dom/base/LinkStyle.h b/dom/base/LinkStyle.h
new file mode 100644
index 0000000000..6ba9992195
--- /dev/null
+++ b/dom/base/LinkStyle.h
@@ -0,0 +1,285 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#ifndef mozilla_dom_LinkStyle_h
+#define mozilla_dom_LinkStyle_h
+
+#include "nsINode.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/StyleSheet.h"
+#include "mozilla/Result.h"
+#include "mozilla/Unused.h"
+#include "nsTArray.h"
+
+class nsIContent;
+class nsICSSLoaderObserver;
+class nsIPrincipal;
+class nsIURI;
+
+namespace mozilla {
+
+namespace dom {
+
+class Document;
+class ShadowRoot;
+
+// https://drafts.csswg.org/cssom/#the-linkstyle-interface
+class LinkStyle {
+ public:
+  enum class ForceUpdate : uint8_t {
+    No,
+    Yes,
+  };
+
+  enum class Completed : uint8_t {
+    No,
+    Yes,
+  };
+
+  enum class HasAlternateRel : uint8_t {
+    No,
+    Yes,
+  };
+
+  enum class IsAlternate : uint8_t {
+    No,
+    Yes,
+  };
+
+  enum class IsInline : uint8_t {
+    No,
+    Yes,
+  };
+
+  enum class IsExplicitlyEnabled : uint8_t {
+    No,
+    Yes,
+  };
+
+  enum class MediaMatched : uint8_t {
+    Yes,
+    No,
+  };
+
+  struct Update {
+   private:
+    bool mWillNotify;
+    bool mIsAlternate;
+    bool mMediaMatched;
+
+   public:
+    Update() : mWillNotify(false), mIsAlternate(false), mMediaMatched(false) {}
+
+    Update(Completed aCompleted, IsAlternate aIsAlternate,
+           MediaMatched aMediaMatched)
+        : mWillNotify(aCompleted == Completed::No),
+          mIsAlternate(aIsAlternate == IsAlternate::Yes),
+          mMediaMatched(aMediaMatched == MediaMatched::Yes) {}
+
+    bool WillNotify() const { return mWillNotify; }
+
+    bool ShouldBlock() const {
+      if (!mWillNotify) {
+        return false;
+      }
+
+      return !mIsAlternate && mMediaMatched;
+    }
+  };
+
+  static LinkStyle* FromNode(nsINode& aNode) { return aNode.AsLinkStyle(); }
+  static const LinkStyle* FromNode(const nsINode& aNode) {
+    return aNode.AsLinkStyle();
+  }
+
+  static LinkStyle* FromNodeOrNull(nsINode* aNode) {
+    return aNode ? FromNode(*aNode) : nullptr;
+  }
+
+  static const LinkStyle* FromNodeOrNull(const nsINode* aNode) {
+    return aNode ? FromNode(*aNode) : nullptr;
+  }
+
+  enum RelValue {
+    ePREFETCH = 0x00000001,
+    eDNS_PREFETCH = 0x00000002,
+    eSTYLESHEET = 0x00000004,
+    eNEXT = 0x00000008,
+    eALTERNATE = 0x00000010,
+    ePRECONNECT = 0x00000020,
+    // NOTE: 0x40 is unused
+    ePRELOAD = 0x00000080
+  };
+
+  // The return value is a bitwise or of 0 or more RelValues.
+  static uint32_t ParseLinkTypes(const nsAString& aTypes);
+
+  void UpdateStyleSheetInternal() {
+    Unused << UpdateStyleSheetInternal(nullptr, nullptr);
+  }
+
+  struct MOZ_STACK_CLASS SheetInfo {
+    nsIContent* mContent;
+    // FIXME(emilio): do these really need to be strong refs?
+    nsCOMPtr<nsIURI> mURI;
+
+    // The principal of the scripted caller that initiated the load, if
+    // available. Otherwise null.
+    nsCOMPtr<nsIPrincipal> mTriggeringPrincipal;
+    nsCOMPtr<nsIReferrerInfo> mReferrerInfo;
+    mozilla::CORSMode mCORSMode;
+    nsString mTitle;
+    nsString mMedia;
+    nsString mIntegrity;
+    nsString mNonce;
+
+    bool mHasAlternateRel;
+    bool mIsInline;
+    IsExplicitlyEnabled mIsExplicitlyEnabled;
+
+    SheetInfo(const mozilla::dom::Document&, nsIContent*,
+              already_AddRefed<nsIURI> aURI,
+              already_AddRefed<nsIPrincipal> aTriggeringPrincipal,
+              already_AddRefed<nsIReferrerInfo> aReferrerInfo,
+              mozilla::CORSMode, const nsAString& aTitle,
+              const nsAString& aMedia, const nsAString& aIntegrity,
+              const nsAString& aNonce, HasAlternateRel, IsInline,
+              IsExplicitlyEnabled);
+
+    ~SheetInfo();
+  };
+
+  virtual nsIContent& AsContent() = 0;
+  virtual Maybe<SheetInfo> GetStyleSheetInfo() = 0;
+
+  /**
+   * Used to make the association between a style sheet and
+   * the element that linked it to the document.
+   *
+   * @param aStyleSheet the style sheet associated with this
+   *                    element.
+   */
+  void SetStyleSheet(StyleSheet* aStyleSheet);
+
+  /**
+   * Tells this element to update the stylesheet.
+   *
+   * @param aObserver    observer to notify once the stylesheet is loaded.
+   *                     This will be passed to the CSSLoader
+   */
+  Result<Update, nsresult> UpdateStyleSheet(nsICSSLoaderObserver*);
+
+  /**
+   * Tells this element whether to update the stylesheet when the
+   * element's properties change.
+   *
+   * @param aEnableUpdates update on changes or not.
+   */
+  void SetEnableUpdates(bool aEnableUpdates) {
+    mUpdatesEnabled = aEnableUpdates;
+  }
+
+  /**
+   * Gets the charset that the element claims the style sheet is in.
+   * Can return empty string to indicate that we have no charset
+   * information.
+   *
+   * @param aCharset the charset
+   */
+  virtual void GetCharset(nsAString& aCharset);
+
+  // This doesn't entirely belong here since they only make sense for
+  // some types of linking elements, but it's a better place than
+  // anywhere else.
+  void SetLineNumber(uint32_t aLineNumber) { mLineNumber = aLineNumber; }
+
+  /**
+   * Get the line number, as previously set by SetLineNumber.
+   *
+   * @return the line number of this element; or 1 if no line number
+   *         was set
+   */
+  uint32_t GetLineNumber() const { return mLineNumber; }
+
+  // This doesn't entirely belong here since they only make sense for
+  // some types of linking elements, but it's a better place than
+  // anywhere else.
+  void SetColumnNumber(uint32_t aColumnNumber) {
+    mColumnNumber = aColumnNumber;
+  }
+
+  /**
+   * Get the column number, as previously set by SetColumnNumber.
+   *
+   * @return the column number of this element; or 1 if no column number
+   *         was set
+   */
+  uint32_t GetColumnNumber() const { return mColumnNumber; }
+
+  StyleSheet* GetSheet() const { return mStyleSheet; }
+
+ protected:
+  LinkStyle();
+  virtual ~LinkStyle();
+
+  // Gets a suitable title and media for SheetInfo out of an element, which
+  // needs to be `this`.
+  //
+  // NOTE(emilio): Needs nsString instead of nsAString because of
+  // CompressWhitespace.
+  static void GetTitleAndMediaForElement(const mozilla::dom::Element&,
+                                         nsString& aTitle, nsString& aMedia);
+
+  // Returns whether the type attribute specifies the text/css type for style
+  // elements.
+  static bool IsCSSMimeTypeAttributeForStyleElement(const Element&);
+
+  // CC methods
+  void Unlink();
+  void Traverse(nsCycleCollectionTraversalCallback& cb);
+
+  /**
+   * @param aOldDocument   should be non-null only if we're updating because we
+   *                       removed the node from the document.
+   * @param aOldShadowRoot should be non-null only if we're updating because we
+   *                       removed the node from a shadow tree.
+   * @param aForceUpdate true will force the update even if the URI has not
+   *                     changed.  This should be used in cases when something
+   *                     about the content that affects the resulting sheet
+   *                     changed but the URI may not have changed.
+   *
+   * TODO(emilio): Should probably pass a single DocumentOrShadowRoot.
+   */
+  Result<Update, nsresult> UpdateStyleSheetInternal(
+      Document* aOldDocument, ShadowRoot* aOldShadowRoot,
+      ForceUpdate = ForceUpdate::No);
+
+  /**
+   * @param aOldDocument should be non-null only if we're updating because we
+   *                     removed the node from the document.
+   * @param aOldShadowRoot The ShadowRoot that used to contain the style.
+   *                     Passed as a parameter because on an update, the node
+   *                     is removed from the tree before the sheet is removed
+   *                     from the ShadowRoot.
+   * @param aForceUpdate true will force the update even if the URI has not
+   *                     changed.  This should be used in cases when something
+   *                     about the content that affects the resulting sheet
+   *                     changed but the URI may not have changed.
+   */
+  Result<Update, nsresult> DoUpdateStyleSheet(Document* aOldDocument,
+                                              ShadowRoot* aOldShadowRoot,
+                                              nsICSSLoaderObserver*,
+                                              ForceUpdate);
+
+  RefPtr<mozilla::StyleSheet> mStyleSheet;
+  nsCOMPtr<nsIPrincipal> mTriggeringPrincipal;
+  bool mUpdatesEnabled;
+  uint32_t mLineNumber;
+  uint32_t mColumnNumber;
+};
+
+}  // namespace dom
+
+}  // namespace mozilla
+
+#endif  // mozilla_dom_LinkStyle_h
diff --git a/dom/base/ResizeObserver.cpp b/dom/base/ResizeObserver.cpp
index 0c04974d9c..589a4bf524 100644
--- a/dom/base/ResizeObserver.cpp
+++ b/dom/base/ResizeObserver.cpp
@@ -87,10 +87,47 @@ static nsSize GetTargetSize(Element* aTarget, ResizeObserverBoxOptions aBox) {
   return size;
 }
 
-NS_IMPL_CYCLE_COLLECTION(ResizeObservation, mTarget)
+NS_IMPL_CYCLE_COLLECTION_CLASS(ResizeObservation)
+
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(ResizeObservation)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mTarget);
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(ResizeObservation)
+  tmp->Unlink(RemoveFromObserver::Yes);
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+
 NS_IMPL_CYCLE_COLLECTION_ROOT_NATIVE(ResizeObservation, AddRef)
 NS_IMPL_CYCLE_COLLECTION_UNROOT_NATIVE(ResizeObservation, Release)
 
+ResizeObservation::ResizeObservation(Element& aTarget,
+                                     ResizeObserver& aObserver,
+                                     ResizeObserverBoxOptions aBox,
+                                     WritingMode aWm)
+    : mTarget(&aTarget),
+      mObserver(&aObserver),
+      mObservedBox(aBox),
+      // This starts us with a 0,0 last-reported-size:
+      mLastReportedSize(aWm),
+      mLastReportedWM(aWm) {
+  aTarget.BindObject(mObserver);
+}
+
+void ResizeObservation::Unlink(RemoveFromObserver aRemoveFromObserver) {
+  ResizeObserver* observer = std::exchange(mObserver, nullptr);
+  nsCOMPtr<Element> target = std::move(mTarget);
+  if (observer && target) {
+    if (aRemoveFromObserver == RemoveFromObserver::Yes) {
+      IgnoredErrorResult rv;
+      observer->Unobserve(*target, rv);
+      MOZ_DIAGNOSTIC_ASSERT(!rv.Failed(),
+                            "How could we keep the observer and target around "
+                            "without being in the observation map?");
+    }
+    target->UnbindObject(observer);
+  }
+}
+
 bool ResizeObservation::IsActive() const {
   nsIFrame* frame = mTarget->GetPrimaryFrame();
   const WritingMode wm = frame ? frame->GetWritingMode() : WritingMode();
@@ -106,9 +143,22 @@ void ResizeObservation::UpdateLastReportedSize(const nsSize& aSize) {
 }
 
 // Only needed for refcounted objects.
-NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(ResizeObserver, mOwner, mDocument,
-                                      mCallback, mActiveTargets,
-                                      mObservationMap)
+NS_IMPL_CYCLE_COLLECTION_CLASS(ResizeObserver)
+
+NS_IMPL_CYCLE_COLLECTION_TRACE_WRAPPERCACHE(ResizeObserver)
+
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(ResizeObserver)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mOwner, mDocument, mCallback,
+                                    mActiveTargets, mObservationMap);
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(ResizeObserver)
+  tmp->Disconnect();
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mOwner, mDocument, mCallback, mActiveTargets,
+                                  mObservationMap);
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_PRESERVED_WRAPPER
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+
 NS_IMPL_CYCLE_COLLECTING_ADDREF(ResizeObserver)
 NS_IMPL_CYCLE_COLLECTING_RELEASE(ResizeObserver)
 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(ResizeObserver)
@@ -150,7 +200,7 @@ void ResizeObserver::Observe(Element& aTarget,
   }
 
   RefPtr<ResizeObservation>& observation =
-    mObservationMap.LookupForAdd(&aTarget).OrInsert([] { return nullptr; });
+      mObservationMap.LookupForAdd(&aTarget).OrInsert([] { return nullptr; });
   if (observation) {
     if (observation->BoxOptions() == aOptions.mBox) {
       // Already observed this target and the observed box is the same, so
@@ -171,8 +221,9 @@ void ResizeObserver::Observe(Element& aTarget,
   // FIXME(emilio): This should probably either flush or not look at the
   // writing-mode or something.
   nsIFrame* frame = aTarget.GetPrimaryFrame();
-  observation = new ResizeObservation(
-      aTarget, aOptions.mBox, frame ? frame->GetWritingMode() : WritingMode());
+  observation =
+      new ResizeObservation(aTarget, *this, aOptions.mBox,
+                            frame ? frame->GetWritingMode() : WritingMode());
   mObservationList.insertBack(observation);
 
   // Per the spec, we need to trigger notification in event loop that
@@ -200,7 +251,10 @@ void ResizeObserver::Unobserve(Element& aTarget, ErrorResult& aRv) {
 
 void ResizeObserver::Disconnect() {
   const bool registered = !mObservationList.isEmpty();
-  mObservationList.clear();
+  while (auto* observation = mObservationList.popFirst()) {
+    observation->Unlink(ResizeObservation::RemoveFromObserver::No);
+  }
+  MOZ_ASSERT(mObservationList.isEmpty());
   mObservationMap.Clear();
   mActiveTargets.Clear();
   if (registered && MOZ_LIKELY(mDocument)) {
@@ -288,6 +342,30 @@ NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(ResizeObserverEntry)
   NS_INTERFACE_MAP_ENTRY(nsISupports)
 NS_INTERFACE_MAP_END
 
+void ResizeObserverEntry::GetBorderBoxSize(
+    nsTArray<RefPtr<ResizeObserverSize>>& aRetVal) const {
+  // In the resize-observer-1 spec, there will only be a single
+  // ResizeObserverSize returned in the FrozenArray for now.
+  //
+  // Note: the usage of FrozenArray is to support elements that have multiple
+  // fragments, which occur in multi-column scenarios.
+  // https://drafts.csswg.org/resize-observer/#resize-observer-entry-interface
+  aRetVal.Clear();
+  aRetVal.AppendElement(mBorderBoxSize);
+}
+
+void ResizeObserverEntry::GetContentBoxSize(
+    nsTArray<RefPtr<ResizeObserverSize>>& aRetVal) const {
+  // In the resize-observer-1 spec, there will only be a single
+  // ResizeObserverSize returned in the FrozenArray for now.
+  //
+  // Note: the usage of FrozenArray is to support elements that have multiple
+  // fragments, which occur in multi-column scenarios.
+  // https://drafts.csswg.org/resize-observer/#resize-observer-entry-interface
+  aRetVal.Clear();
+  aRetVal.AppendElement(mContentBoxSize);
+}
+
 void ResizeObserverEntry::SetBorderBoxSize(const nsSize& aSize) {
   nsIFrame* frame = mTarget->GetPrimaryFrame();
   const WritingMode wm = frame ? frame->GetWritingMode() : WritingMode();
diff --git a/dom/base/ResizeObserver.h b/dom/base/ResizeObserver.h
index ab98813473..abdac3f625 100644
--- a/dom/base/ResizeObserver.h
+++ b/dom/base/ResizeObserver.h
@@ -24,12 +24,6 @@ namespace dom {
 
 class Element;
 
-}  // namespace dom
-}  // namespace mozilla
-
-namespace mozilla {
-namespace dom {
-
 // For the internal implementation in ResizeObserver. Normally, this is owned by
 // ResizeObserver.
 class ResizeObservation final : public LinkedListElement<ResizeObservation> {
@@ -37,15 +31,8 @@ class ResizeObservation final : public LinkedListElement<ResizeObservation> {
   NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING(ResizeObservation)
   NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS(ResizeObservation)
 
-  ResizeObservation(Element& aTarget, ResizeObserverBoxOptions aBox,
-                    const WritingMode aWM)
-      : mTarget(&aTarget),
-        mObservedBox(aBox),
-        // This starts us with a 0,0 last-reported-size:
-        mLastReportedSize(aWM),
-        mLastReportedWM(aWM) {
-    MOZ_ASSERT(mTarget, "Need a non-null target element");
-  }
+  ResizeObservation(Element&, ResizeObserver&, ResizeObserverBoxOptions,
+                    WritingMode);
 
   Element* Target() const { return mTarget; }
 
@@ -62,11 +49,17 @@ class ResizeObservation final : public LinkedListElement<ResizeObservation> {
    */
   void UpdateLastReportedSize(const nsSize& aSize);
 
+  enum class RemoveFromObserver : bool { No, Yes };
+  void Unlink(RemoveFromObserver);
+
  protected:
-  ~ResizeObservation() = default;
+  ~ResizeObservation() { Unlink(RemoveFromObserver::No); };
 
   nsCOMPtr<Element> mTarget;
 
+  // Weak, observer always outlives us.
+  ResizeObserver* mObserver;
+
   const ResizeObserverBoxOptions mObservedBox;
 
   // The latest recorded size of observed target.
@@ -144,7 +137,7 @@ class ResizeObserver final : public nsISupports, public nsWrapperCache {
   MOZ_CAN_RUN_SCRIPT uint32_t BroadcastActiveObservations();
 
  protected:
-  ~ResizeObserver() { mObservationList.clear(); }
+  ~ResizeObserver() { Disconnect(); }
 
   nsCOMPtr<nsPIDOMWindowInner> mOwner;
   // The window's document at the time of ResizeObserver creation.
@@ -207,8 +200,8 @@ class ResizeObserverEntry final : public nsISupports, public nsWrapperCache {
    * Returns target's logical border-box size and content-box size as
    * ResizeObserverSize.
    */
-  ResizeObserverSize* BorderBoxSize() const { return mBorderBoxSize; }
-  ResizeObserverSize* ContentBoxSize() const { return mContentBoxSize; }
+  void GetBorderBoxSize(nsTArray<RefPtr<ResizeObserverSize>>& aRetVal) const;
+  void GetContentBoxSize(nsTArray<RefPtr<ResizeObserverSize>>& aRetVal) const;
 
  private:
   ~ResizeObserverEntry() = default;
diff --git a/dom/base/ResizeObserverController.cpp b/dom/base/ResizeObserverController.cpp
index 2c1ff3b581..47f83029ef 100644
--- a/dom/base/ResizeObserverController.cpp
+++ b/dom/base/ResizeObserverController.cpp
@@ -73,13 +73,6 @@ ResizeObserverNotificationHelper::~ResizeObserverNotificationHelper() {
   MOZ_RELEASE_ASSERT(!mOwner, "Forgot to clear weak pointer?");
 }
 
-void ResizeObserverController::Traverse(
-    nsCycleCollectionTraversalCallback& aCb) {
-  ImplCycleCollectionTraverse(aCb, mResizeObservers, "mResizeObservers");
-}
-
-void ResizeObserverController::Unlink() { mResizeObservers.Clear(); }
-
 void ResizeObserverController::ShellDetachedFromDocument() {
   mResizeObserverNotificationHelper->Unregister();
 }
diff --git a/dom/base/ResizeObserverController.h b/dom/base/ResizeObserverController.h
index 1cb7c250bb..40b25368ea 100644
--- a/dom/base/ResizeObserverController.h
+++ b/dom/base/ResizeObserverController.h
@@ -64,10 +64,6 @@ class ResizeObserverController final {
     MOZ_ASSERT(mDocument, "Need a non-null document");
   }
 
-  // Methods for supporting cycle-collection
-  void Traverse(nsCycleCollectionTraversalCallback& aCb);
-  void Unlink();
-
   void AddSizeOfIncludingThis(nsWindowSizes&) const;
 
   void ShellDetachedFromDocument();
diff --git a/dom/base/ResponsiveImageSelector.h b/dom/base/ResponsiveImageSelector.h
index de68764ab6..66a6765c4d 100644
--- a/dom/base/ResponsiveImageSelector.h
+++ b/dom/base/ResponsiveImageSelector.h
@@ -7,7 +7,6 @@
 
 #include "mozilla/UniquePtr.h"
 #include "mozilla/ServoBindingTypes.h"
-#include "nsAutoPtr.h"
 #include "nsISupports.h"
 #include "nsIContent.h"
 #include "nsString.h"
diff --git a/dom/base/ShadowRoot.cpp b/dom/base/ShadowRoot.cpp
index e9ae5f5f9f..9f410cf8d7 100644
--- a/dom/base/ShadowRoot.cpp
+++ b/dom/base/ShadowRoot.cpp
@@ -8,7 +8,6 @@
 #include "mozilla/dom/DocumentFragment.h"
 #include "ChildIterator.h"
 #include "nsContentUtils.h"
-#include "nsIStyleSheetLinkingElement.h"
 #include "nsWindowSizes.h"
 #include "nsXBLPrototypeBinding.h"
 #include "mozilla/dom/DirectionalityUtils.h"
diff --git a/dom/base/StructuredCloneHolder.h b/dom/base/StructuredCloneHolder.h
index b36941ec3c..685507801d 100644
--- a/dom/base/StructuredCloneHolder.h
+++ b/dom/base/StructuredCloneHolder.h
@@ -5,11 +5,12 @@
 #ifndef mozilla_dom_StructuredCloneHolder_h
 #define mozilla_dom_StructuredCloneHolder_h
 
-#include "jsapi.h"
+#include <utility>
+
 #include "js/StructuredClone.h"
 #include "js/WasmModule.h"
+#include "jsapi.h"
 #include "mozilla/MemoryReporting.h"
-#include "mozilla/Move.h"
 #include "mozilla/UniquePtr.h"
 #include "mozilla/dom/BindingDeclarations.h"
 #include "nsTArray.h"
diff --git a/dom/base/ThirdPartyUtil.cpp b/dom/base/ThirdPartyUtil.cpp
index d1449470fe..a26eb44de5 100644
--- a/dom/base/ThirdPartyUtil.cpp
+++ b/dom/base/ThirdPartyUtil.cpp
@@ -310,8 +310,8 @@ ThirdPartyUtil::IsThirdPartyChannel(nsIChannel* aChannel, nsIURI* aURI,
         // Check if the channel itself is third-party to its own requestor.
         // Unforunately, we have to go through the loading principal.
 
-        rv = loadInfo->LoadingPrincipal()->IsThirdPartyURI(channelURI,
-                                                           &parentIsThird);
+        rv = loadInfo->GetLoadingPrincipal()->IsThirdPartyURI(channelURI,
+                                                              &parentIsThird);
         if (NS_FAILED(rv)) {
           return rv;
         }
diff --git a/dom/base/TimeoutManager.cpp b/dom/base/TimeoutManager.cpp
index 0b8c545eb2..082ece0659 100644
--- a/dom/base/TimeoutManager.cpp
+++ b/dom/base/TimeoutManager.cpp
@@ -280,7 +280,7 @@ bool TimeoutManager::IsInvalidFiringId(uint32_t aFiringId) const {
     // If the first element is bigger than the last element in the
     // stack, that means mNextFiringId wrapped around to zero at
     // some point.
-    Swap(low, high);
+    std::swap(low, high);
   }
   MOZ_DIAGNOSTIC_ASSERT(low < high);
 
diff --git a/dom/base/moz.build b/dom/base/moz.build
index 2928507210..1d0746b638 100644
--- a/dom/base/moz.build
+++ b/dom/base/moz.build
@@ -83,7 +83,6 @@ EXPORTS += [
     'nsIScriptContext.h',
     'nsIScriptGlobalObject.h',
     'nsIScriptObjectPrincipal.h',
-    'nsIStyleSheetLinkingElement.h',
     'nsJSEnvironment.h',
     'nsJSUtils.h',
     'nsLineBreaker.h',
@@ -101,7 +100,6 @@ EXPORTS += [
     'nsStubDocumentObserver.h',
     'nsStubMutationObserver.h',
     'nsStyledElement.h',
-    'nsStyleLinkElement.h',
     'nsTextFragment.h',
     'nsTraversal.h',
     'nsTreeSanitizer.h',
@@ -191,6 +189,7 @@ EXPORTS.mozilla.dom += [
     'ImageTracker.h',
     'IntlUtils.h',
     'Link.h',
+    'LinkStyle.h',
     'Location.h',
     'MaybeCrossOriginObject.h',
     'MessageBroadcaster.h',
@@ -309,6 +308,7 @@ UNIFIED_SOURCES += [
     'InProcessBrowserChildMessageManager.cpp',
     'IntlUtils.cpp',
     'Link.cpp',
+    'LinkStyle.cpp',
     'Location.cpp',
     'MaybeCrossOriginObject.cpp',
     'MessageBroadcaster.cpp',
@@ -369,7 +369,6 @@ UNIFIED_SOURCES += [
     'nsStubDocumentObserver.cpp',
     'nsStubMutationObserver.cpp',
     'nsStyledElement.cpp',
-    'nsStyleLinkElement.cpp',
     'nsSyncLoadService.cpp',
     'nsTextFragment.cpp',
     'nsTextNode.cpp',
diff --git a/dom/base/nsAttrValue.cpp b/dom/base/nsAttrValue.cpp
index 4638a51904..d71b90d6d7 100644
--- a/dom/base/nsAttrValue.cpp
+++ b/dom/base/nsAttrValue.cpp
@@ -38,7 +38,7 @@ using namespace mozilla;
 MiscContainer* nsAttrValue::AllocMiscContainer() {
   MOZ_ASSERT(NS_IsMainThread());
   MiscContainer* cont = nullptr;
-  Swap(cont, sMiscContainerCache);
+  std::swap(cont, sMiscContainerCache);
 
   if (cont) {
     return new (cont) MiscContainer;
diff --git a/dom/base/nsContentPolicy.cpp b/dom/base/nsContentPolicy.cpp
index cace2dcdde..3d183520a0 100644
--- a/dom/base/nsContentPolicy.cpp
+++ b/dom/base/nsContentPolicy.cpp
@@ -68,7 +68,7 @@ inline nsresult nsContentPolicy::CheckPolicy(CPMethod policyMethod,
   nsContentPolicyType contentType = loadInfo->InternalContentPolicyType();
   nsCOMPtr<nsISupports> requestingContext = loadInfo->GetLoadingContext();
   nsCOMPtr<nsIURI> requestingLocation;
-  nsCOMPtr<nsIPrincipal> loadingPrincipal = loadInfo->LoadingPrincipal();
+  nsCOMPtr<nsIPrincipal> loadingPrincipal = loadInfo->GetLoadingPrincipal();
   if (loadingPrincipal) {
     loadingPrincipal->GetURI(getter_AddRefs(requestingLocation));
   }
@@ -164,7 +164,7 @@ inline nsresult nsContentPolicy::CheckPolicy(CPMethod policyMethod,
 #define LOG_CHECK(logType)                                                     \
   PR_BEGIN_MACRO                                                               \
   nsCOMPtr<nsIURI> requestingLocation;                                         \
-  nsCOMPtr<nsIPrincipal> loadingPrincipal = loadInfo->LoadingPrincipal();      \
+  nsCOMPtr<nsIPrincipal> loadingPrincipal = loadInfo->GetLoadingPrincipal();   \
   if (loadingPrincipal) {                                                      \
     loadingPrincipal->GetURI(getter_AddRefs(requestingLocation));              \
   }                                                                            \
diff --git a/dom/base/nsContentPolicyUtils.h b/dom/base/nsContentPolicyUtils.h
index 687451fcf1..f9e3649dff 100644
--- a/dom/base/nsContentPolicyUtils.h
+++ b/dom/base/nsContentPolicyUtils.h
@@ -138,6 +138,9 @@ inline const char* NS_CP_ContentTypeName(uint32_t contentType) {
     CASE_RETURN(TYPE_INTERNAL_MODULE_PRELOAD);
     CASE_RETURN(TYPE_INTERNAL_DTD);
     CASE_RETURN(TYPE_INTERNAL_FORCE_ALLOWED_DTD);
+    CASE_RETURN(TYPE_INTERNAL_AUDIOWORKLET);
+    CASE_RETURN(TYPE_INTERNAL_PAINTWORKLET);
+    CASE_RETURN(TYPE_INTERNAL_FONT_PRELOAD);
     default:
       return "<Unknown Type>";
   }
@@ -168,44 +171,38 @@ inline const char* NS_CP_ContentTypeName(uint32_t contentType) {
  * Note: requestOrigin is scoped outside the PR_BEGIN_MACRO/PR_END_MACRO on
  * purpose */
 #define CHECK_PRINCIPAL_CSP_AND_DATA(action)                                  \
-  nsCOMPtr<nsIURI> requestOrigin;                                             \
   PR_BEGIN_MACRO                                                              \
-  if (loadingPrincipal) {                                                     \
+  if (loadingPrincipal && loadingPrincipal->IsSystemPrincipal()) {            \
     /* We exempt most loads into any document with the system principal       \
-     * from content policy (escept CSP) checks, mostly as an optimization.    \
+     * from content policy (except CSP) checks, mostly as an optimization.    \
      * Which means that we need to apply this check to the loading principal, \
      * not the principal that triggered the load. */                          \
-    bool isSystem = loadingPrincipal->IsSystemPrincipal();                    \
-    if (isSystem) {                                                           \
-      /* Check CSP for System Privileged pages */                             \
-      CSPService::ConsultCSP(contentLocation, loadInfo, mimeType, decision);  \
-      if (NS_CP_REJECTED(*decision)) {                                        \
-        return NS_OK;                                                         \
+    /* Check CSP for System Privileged pages */                               \
+    CSPService::ConsultCSP(contentLocation, loadInfo, mimeType, decision);    \
+    if (NS_CP_REJECTED(*decision)) {                                          \
+      return NS_OK;                                                           \
+    }                                                                         \
+    if (contentType != nsIContentPolicy::TYPE_DOCUMENT) {                     \
+      *decision = nsIContentPolicy::ACCEPT;                                   \
+      nsCOMPtr<nsINode> n = do_QueryInterface(context);                       \
+      if (!n) {                                                               \
+        nsCOMPtr<nsPIDOMWindowOuter> win = do_QueryInterface(context);        \
+        n = win ? win->GetExtantDoc() : nullptr;                              \
       }                                                                       \
-      if (contentType != nsIContentPolicy::TYPE_DOCUMENT) {                   \
-        *decision = nsIContentPolicy::ACCEPT;                                 \
-        nsCOMPtr<nsINode> n = do_QueryInterface(context);                     \
-        if (!n) {                                                             \
-          nsCOMPtr<nsPIDOMWindowOuter> win = do_QueryInterface(context);      \
-          n = win ? win->GetExtantDoc() : nullptr;                            \
-        }                                                                     \
-        if (n) {                                                              \
-          mozilla::dom::Document* d = n->OwnerDoc();                          \
-          if (d->IsLoadedAsData() || d->IsBeingUsedAsImage() ||               \
-              d->IsResourceDoc()) {                                           \
-            nsCOMPtr<nsIContentPolicy> dataPolicy =                           \
-                do_GetService("@mozilla.org/data-document-content-policy;1"); \
-            if (dataPolicy) {                                                 \
-              dataPolicy->action(contentLocation, loadInfo, mimeType,         \
-                                 decision);                                   \
-            }                                                                 \
+      if (n) {                                                                \
+        mozilla::dom::Document* d = n->OwnerDoc();                            \
+        if (d->IsLoadedAsData() || d->IsBeingUsedAsImage() ||                 \
+            d->IsResourceDoc()) {                                             \
+          nsCOMPtr<nsIContentPolicy> dataPolicy =                             \
+              do_GetService("@mozilla.org/data-document-content-policy;1");   \
+          if (dataPolicy) {                                                   \
+            dataPolicy->action(contentLocation, loadInfo, mimeType,           \
+                               decision);                                     \
           }                                                                   \
         }                                                                     \
       }                                                                       \
-      return NS_OK;                                                           \
     }                                                                         \
-    nsresult rv = loadingPrincipal->GetURI(getter_AddRefs(requestOrigin));    \
-    NS_ENSURE_SUCCESS(rv, rv);                                                \
+    return NS_OK;                                                             \
   }                                                                           \
   PR_END_MACRO
 
@@ -222,7 +219,7 @@ inline const char* NS_CP_ContentTypeName(uint32_t contentType) {
 inline nsresult NS_CheckContentLoadPolicy(
     nsIURI* contentLocation, nsILoadInfo* loadInfo, const nsACString& mimeType,
     int16_t* decision, nsIContentPolicy* policyService = nullptr) {
-  nsIPrincipal* loadingPrincipal = loadInfo->LoadingPrincipal();
+  nsIPrincipal* loadingPrincipal = loadInfo->GetLoadingPrincipal();
   nsCOMPtr<nsISupports> context = loadInfo->GetLoadingContext();
   nsContentPolicyType contentType = loadInfo->InternalContentPolicyType();
   CHECK_PRINCIPAL_CSP_AND_DATA(ShouldLoad);
@@ -238,7 +235,7 @@ inline nsresult NS_CheckContentLoadPolicy(
 inline nsresult NS_CheckContentProcessPolicy(
     nsIURI* contentLocation, nsILoadInfo* loadInfo, const nsACString& mimeType,
     int16_t* decision, nsIContentPolicy* policyService = nullptr) {
-  nsIPrincipal* loadingPrincipal = loadInfo->LoadingPrincipal();
+  nsIPrincipal* loadingPrincipal = loadInfo->GetLoadingPrincipal();
   nsCOMPtr<nsISupports> context = loadInfo->GetLoadingContext();
   nsContentPolicyType contentType = loadInfo->InternalContentPolicyType();
   CHECK_PRINCIPAL_CSP_AND_DATA(ShouldProcess);
diff --git a/dom/base/nsContentSink.cpp b/dom/base/nsContentSink.cpp
index fc9f622100..97113462d1 100644
--- a/dom/base/nsContentSink.cpp
+++ b/dom/base/nsContentSink.cpp
@@ -11,10 +11,10 @@
 #include "mozilla/Components.h"
 #include "mozilla/PresShell.h"
 #include "mozilla/dom/Document.h"
-#include "mozilla/dom/MutationObservers.h"
+#include "mozilla/dom/LinkStyle.h"
 #include "mozilla/css/Loader.h"
+#include "mozilla/dom/MutationObservers.h"
 #include "mozilla/dom/SRILogHelper.h"
-#include "nsStyleLinkElement.h"
 #include "nsIDocShell.h"
 #include "nsILoadContext.h"
 #include "nsIPrefetchService.h"
@@ -279,8 +279,8 @@ nsresult nsContentSink::ProcessHeaderData(nsAtom* aHeader,
       mParser->GetChannel(getter_AddRefs(channel));
     }
 
-    rv = cookieServ->SetCookieString(codebaseURI, nullptr,
-                                     NS_ConvertUTF16toUTF8(aValue), channel);
+    rv = cookieServ->SetCookieString(codebaseURI, NS_ConvertUTF16toUTF8(aValue),
+                                     channel);
     if (NS_FAILED(rv)) {
       return rv;
     }
@@ -385,6 +385,9 @@ nsresult nsContentSink::ProcessLinkHeader(const nsAString& aLinkData) {
   nsAutoString rel;
   nsAutoString title;
   nsAutoString titleStar;
+  nsAutoString integrity;
+  nsAutoString srcset;
+  nsAutoString sizes;
   nsAutoString type;
   nsAutoString media;
   nsAutoString anchor;
@@ -588,6 +591,18 @@ nsresult nsContentSink::ProcessLinkHeader(const nsAString& aLinkData) {
             if (referrerPolicy.IsEmpty()) {
               referrerPolicy = value;
             }
+          } else if (attr.LowerCaseEqualsLiteral("integrity")) {
+            if (integrity.IsEmpty()) {
+              integrity = value;
+            }
+          } else if (attr.LowerCaseEqualsLiteral("imagesrcset")) {
+            if (srcset.IsEmpty()) {
+              srcset = value;
+            }
+          } else if (attr.LowerCaseEqualsLiteral("imagesizes")) {
+            if (sizes.IsEmpty()) {
+              sizes = value;
+            }
           }
         }
       }
@@ -601,14 +616,17 @@ nsresult nsContentSink::ProcessLinkHeader(const nsAString& aLinkData) {
         rv = ProcessLinkFromHeader(
             anchor, href, rel,
             // prefer RFC 5987 variant over non-I18zed version
-            titleStar.IsEmpty() ? title : titleStar, type, media, crossOrigin,
-            referrerPolicy, as);
+            titleStar.IsEmpty() ? title : titleStar, integrity, srcset, sizes,
+            type, media, crossOrigin, referrerPolicy, as);
       }
 
       href.Truncate();
       rel.Truncate();
       title.Truncate();
       type.Truncate();
+      integrity.Truncate();
+      srcset.Truncate();
+      sizes.Truncate();
       media.Truncate();
       anchor.Truncate();
       referrerPolicy.Truncate();
@@ -623,11 +641,11 @@ nsresult nsContentSink::ProcessLinkHeader(const nsAString& aLinkData) {
 
   href.Trim(" \t\n\r\f");  // trim HTML5 whitespace
   if (!href.IsEmpty() && !rel.IsEmpty()) {
-    rv =
-        ProcessLinkFromHeader(anchor, href, rel,
-                              // prefer RFC 5987 variant over non-I18zed version
-                              titleStar.IsEmpty() ? title : titleStar, type,
-                              media, crossOrigin, referrerPolicy, as);
+    rv = ProcessLinkFromHeader(
+        anchor, href, rel,
+        // prefer RFC 5987 variant over non-I18zed version
+        titleStar.IsEmpty() ? title : titleStar, integrity, srcset, sizes, type,
+        media, crossOrigin, referrerPolicy, as);
   }
 
   return rv;
@@ -635,10 +653,11 @@ nsresult nsContentSink::ProcessLinkHeader(const nsAString& aLinkData) {
 
 nsresult nsContentSink::ProcessLinkFromHeader(
     const nsAString& aAnchor, const nsAString& aHref, const nsAString& aRel,
-    const nsAString& aTitle, const nsAString& aType, const nsAString& aMedia,
-    const nsAString& aCrossOrigin, const nsAString& aReferrerPolicy,
-    const nsAString& aAs) {
-  uint32_t linkTypes = nsStyleLinkElement::ParseLinkTypes(aRel);
+    const nsAString& aTitle, const nsAString& aIntegrity,
+    const nsAString& aSrcset, const nsAString& aSizes, const nsAString& aType,
+    const nsAString& aMedia, const nsAString& aCrossOrigin,
+    const nsAString& aReferrerPolicy, const nsAString& aAs) {
+  uint32_t linkTypes = LinkStyle::ParseLinkTypes(aRel);
 
   // The link relation may apply to a different resource, specified
   // in the anchor parameter. For the link relations supported so far,
@@ -650,35 +669,38 @@ nsresult nsContentSink::ProcessLinkFromHeader(
 
   if (nsContentUtils::PrefetchPreloadEnabled(mDocShell)) {
     // prefetch href if relation is "next" or "prefetch"
-    if ((linkTypes & nsStyleLinkElement::eNEXT) ||
-        (linkTypes & nsStyleLinkElement::ePREFETCH) ||
-        (linkTypes & nsStyleLinkElement::ePRELOAD)) {
-      PrefetchPreloadHref(aHref, linkTypes, aAs, aType, aMedia);
+    if ((linkTypes & LinkStyle::eNEXT) || (linkTypes & LinkStyle::ePREFETCH)) {
+      PrefetchHref(aHref, aAs, aType, aMedia);
     }
 
-    if (!aHref.IsEmpty() && (linkTypes & nsStyleLinkElement::eDNS_PREFETCH)) {
+    if (!aHref.IsEmpty() && (linkTypes & LinkStyle::eDNS_PREFETCH)) {
       PrefetchDNS(aHref);
     }
 
-    if (!aHref.IsEmpty() && (linkTypes & nsStyleLinkElement::ePRECONNECT)) {
+    if (!aHref.IsEmpty() && (linkTypes & LinkStyle::ePRECONNECT)) {
       Preconnect(aHref, aCrossOrigin);
     }
+
+    if (linkTypes & LinkStyle::ePRELOAD) {
+      PreloadHref(aHref, aAs, aType, aMedia, aIntegrity, aSrcset, aSizes,
+                  aCrossOrigin, aReferrerPolicy);
+    }
   }
 
   // is it a stylesheet link?
-  if (!(linkTypes & nsStyleLinkElement::eSTYLESHEET)) {
+  if (!(linkTypes & LinkStyle::eSTYLESHEET)) {
     return NS_OK;
   }
 
-  bool isAlternate = linkTypes & nsStyleLinkElement::eALTERNATE;
-  return ProcessStyleLinkFromHeader(aHref, isAlternate, aTitle, aType, aMedia,
-                                    aReferrerPolicy);
+  bool isAlternate = linkTypes & LinkStyle::eALTERNATE;
+  return ProcessStyleLinkFromHeader(aHref, isAlternate, aTitle, aIntegrity,
+                                    aType, aMedia, aReferrerPolicy);
 }
 
 nsresult nsContentSink::ProcessStyleLinkFromHeader(
     const nsAString& aHref, bool aAlternate, const nsAString& aTitle,
-    const nsAString& aType, const nsAString& aMedia,
-    const nsAString& aReferrerPolicy) {
+    const nsAString& aIntegrity, const nsAString& aType,
+    const nsAString& aMedia, const nsAString& aReferrerPolicy) {
   if (aAlternate && aTitle.IsEmpty()) {
     // alternates must have title return without error, for now
     return NS_OK;
@@ -719,7 +741,7 @@ nsresult nsContentSink::ProcessStyleLinkFromHeader(
       CORS_NONE,
       aTitle,
       aMedia,
-      /* integrity = */ EmptyString(),
+      aIntegrity,
       /* nonce = */ EmptyString(),
       aAlternate ? Loader::HasAlternateRel::Yes : Loader::HasAlternateRel::No,
       Loader::IsInline::No,
@@ -788,11 +810,9 @@ nsresult nsContentSink::ProcessMETATag(nsIContent* aContent) {
   return rv;
 }
 
-void nsContentSink::PrefetchPreloadHref(const nsAString& aHref,
-                                        uint32_t aLinkTypes,
-                                        const nsAString& aAs,
-                                        const nsAString& aType,
-                                        const nsAString& aMedia) {
+void nsContentSink::PrefetchHref(const nsAString& aHref, const nsAString& aAs,
+                                 const nsAString& aType,
+                                 const nsAString& aMedia) {
   nsCOMPtr<nsIPrefetchService> prefetchService(components::Prefetch::Service());
   if (prefetchService) {
     // construct URI using document charset
@@ -800,42 +820,49 @@ void nsContentSink::PrefetchPreloadHref(const nsAString& aHref,
     nsCOMPtr<nsIURI> uri;
     NS_NewURI(getter_AddRefs(uri), aHref, encoding, mDocument->GetDocBaseURI());
     if (uri) {
-      bool preload = !!(aLinkTypes & nsStyleLinkElement::ePRELOAD);
-      nsContentPolicyType policyType;
-
-      if (preload) {
-        nsAttrValue asAttr;
-        HTMLLinkElement::ParseAsValue(aAs, asAttr);
-        policyType = HTMLLinkElement::AsValueToContentPolicy(asAttr);
-
-        if (policyType == nsIContentPolicy::TYPE_INVALID) {
-          // Ignore preload with a wrong or empty as attribute.
-          return;
-        }
-
-        nsAutoString mimeType;
-        nsAutoString notUsed;
-        nsContentUtils::SplitMimeType(aType, mimeType, notUsed);
-        if (!HTMLLinkElement::CheckPreloadAttrs(asAttr, mimeType, aMedia,
-                                                mDocument)) {
-          policyType = nsIContentPolicy::TYPE_INVALID;
-        }
-      }
-
       auto referrerInfo = MakeRefPtr<ReferrerInfo>(*mDocument);
       referrerInfo = referrerInfo->CloneWithNewOriginalReferrer(mDocumentURI);
 
-      if (preload) {
-        prefetchService->PreloadURI(uri, referrerInfo, mDocument, policyType);
-      } else {
-        prefetchService->PrefetchURI(
-            uri, referrerInfo, mDocument,
-            aLinkTypes & nsStyleLinkElement::ePREFETCH);
-      }
+      prefetchService->PrefetchURI(uri, referrerInfo, mDocument, true);
     }
   }
 }
 
+void nsContentSink::PreloadHref(const nsAString& aHref, const nsAString& aAs,
+                                const nsAString& aType, const nsAString& aMedia,
+                                const nsAString& aIntegrity,
+                                const nsAString& aSrcset,
+                                const nsAString& aSizes, const nsAString& aCORS,
+                                const nsAString& aReferrerPolicy) {
+  nsAttrValue asAttr;
+  HTMLLinkElement::ParseAsValue(aAs, asAttr);
+  auto policyType = HTMLLinkElement::AsValueToContentPolicy(asAttr);
+
+  if (policyType == nsIContentPolicy::TYPE_INVALID) {
+    // Ignore preload with a wrong or empty as attribute.
+    return;
+  }
+
+  nsAutoString mimeType;
+  nsAutoString notUsed;
+  nsContentUtils::SplitMimeType(aType, mimeType, notUsed);
+  if (!HTMLLinkElement::CheckPreloadAttrs(asAttr, mimeType, aMedia,
+                                          mDocument)) {
+    policyType = nsIContentPolicy::TYPE_INVALID;
+  }
+
+  auto encoding = mDocument->GetDocumentCharacterSet();
+  nsCOMPtr<nsIURI> uri;
+  NS_NewURI(getter_AddRefs(uri), aHref, encoding, mDocument->GetDocBaseURI());
+
+  auto referrerInfo = MakeRefPtr<ReferrerInfo>(*mDocument);
+  referrerInfo = referrerInfo->CloneWithNewOriginalReferrer(mDocumentURI);
+
+  RefPtr<PreloaderBase> preload = mDocument->Preloads().PreloadLinkHeader(
+      uri, aHref, policyType, aAs, aType, aIntegrity, aSrcset, aSizes, aCORS,
+      aReferrerPolicy, referrerInfo);
+}
+
 void nsContentSink::PrefetchDNS(const nsAString& aHref) {
   nsAutoString hostname;
   bool isHttps = false;
@@ -1001,6 +1028,11 @@ void nsContentSink::ProcessOfflineManifest(const nsAString& aManifestSpec) {
     return;
   }
 
+  // If offline storage is disabled skip processing
+  if (!StaticPrefs::browser_cache_offline_storage_enable()) {
+    return;
+  }
+
   // If this document has been interecepted, let's skip the processing of the
   // manifest.
   if (mDocument->GetController().isSome()) {
@@ -1491,12 +1523,11 @@ nsresult nsContentSink::WillParseImpl(void) {
     uint32_t lastEventTime;
     vm->GetLastUserEventTime(lastEventTime);
 
-    bool newDynLower =
-        mDocument->IsInBackgroundWindow() ||
-        ((currentTime - mBeginLoadTime) >
-             StaticPrefs::content_sink_initial_perf_time() &&
-         (currentTime - lastEventTime) <
-             StaticPrefs::content_sink_interactive_time());
+    bool newDynLower = mDocument->IsInBackgroundWindow() ||
+                       ((currentTime - mBeginLoadTime) >
+                            StaticPrefs::content_sink_initial_perf_time() &&
+                        (currentTime - lastEventTime) <
+                            StaticPrefs::content_sink_interactive_time());
 
     if (mDynamicLowerValue != newDynLower) {
       FavorPerformanceHint(!newDynLower, 0);
diff --git a/dom/base/nsContentSink.h b/dom/base/nsContentSink.h
index 076d783793..128696d8c1 100644
--- a/dom/base/nsContentSink.h
+++ b/dom/base/nsContentSink.h
@@ -17,7 +17,6 @@
 #include "nsWeakReference.h"
 #include "nsCOMPtr.h"
 #include "nsString.h"
-#include "nsAutoPtr.h"
 #include "nsGkAtoms.h"
 #include "nsITimer.h"
 #include "nsStubDocumentObserver.h"
@@ -151,20 +150,23 @@ class nsContentSink : public nsICSSLoaderObserver,
   nsresult ProcessLinkHeader(const nsAString& aLinkData);
   nsresult ProcessLinkFromHeader(
       const nsAString& aAnchor, const nsAString& aHref, const nsAString& aRel,
-      const nsAString& aTitle, const nsAString& aType, const nsAString& aMedia,
-      const nsAString& aCrossOrigin, const nsAString& aReferrerPolicy,
-      const nsAString& aAs);
-
-  virtual nsresult ProcessStyleLinkFromHeader(const nsAString& aHref,
-                                              bool aAlternate,
-                                              const nsAString& aTitle,
-                                              const nsAString& aType,
-                                              const nsAString& aMedia,
-                                              const nsAString& aReferrerPolicy);
-
-  void PrefetchPreloadHref(const nsAString& aHref, uint32_t aLinkTypes,
-                           const nsAString& aAs, const nsAString& aType,
-                           const nsAString& aMedia);
+      const nsAString& aTitle, const nsAString& aIntegrity,
+      const nsAString& aSrcset, const nsAString& aSizes, const nsAString& aType,
+      const nsAString& aMedia, const nsAString& aCrossOrigin,
+      const nsAString& aReferrerPolicy, const nsAString& aAs);
+
+  virtual nsresult ProcessStyleLinkFromHeader(
+      const nsAString& aHref, bool aAlternate, const nsAString& aTitle,
+      const nsAString& aIntegrity, const nsAString& aType,
+      const nsAString& aMedia, const nsAString& aReferrerPolicy);
+
+  void PrefetchHref(const nsAString& aHref, const nsAString& aAs,
+                    const nsAString& aType, const nsAString& aMedia);
+  void PreloadHref(const nsAString& aHref, const nsAString& aAs,
+                   const nsAString& aType, const nsAString& aMedia,
+                   const nsAString& aIntegrity, const nsAString& aSrcset,
+                   const nsAString& aSizes, const nsAString& aCORS,
+                   const nsAString& aReferrerPolicy);
 
   // For PrefetchDNS() aHref can either be the usual
   // URI format or of the form "//www.hostname.com" without a scheme.
diff --git a/dom/base/nsContentUtils.cpp b/dom/base/nsContentUtils.cpp
index 8ae89a88c0..56af7f7d08 100644
--- a/dom/base/nsContentUtils.cpp
+++ b/dom/base/nsContentUtils.cpp
@@ -58,6 +58,7 @@
 #include "mozilla/dom/DOMSecurityMonitor.h"
 #include "mozilla/dom/DOMTypes.h"
 #include "mozilla/dom/Element.h"
+#include "mozilla/dom/ElementBinding.h"
 #include "mozilla/dom/ElementInlines.h"
 #include "mozilla/dom/Event.h"
 #include "mozilla/dom/FileSystemSecurity.h"
@@ -1694,8 +1695,8 @@ bool nsContentUtils::OfflineAppAllowed(nsIPrincipal* aPrincipal) {
   nsresult rv = updateService->OfflineAppAllowed(aPrincipal, &allowed);
   return NS_SUCCEEDED(rv) && allowed;
 }
-
-static bool IsErrorPage(nsIURI* aURI) {
+// Static
+bool nsContentUtils::IsErrorPage(nsIURI* aURI) {
   if (!aURI) {
     return false;
   }
@@ -1712,45 +1713,6 @@ static bool IsErrorPage(nsIURI* aURI) {
          name.EqualsLiteral("blocked");
 }
 
-/* static */
-bool nsContentUtils::PrincipalAllowsL10n(nsIPrincipal* aPrincipal,
-                                         nsIURI* aDocumentURI) {
-  if (IsErrorPage(aDocumentURI)) {
-    return true;
-  }
-
-  // The system principal is always allowed.
-  if (aPrincipal->IsSystemPrincipal()) {
-    return true;
-  }
-
-  nsCOMPtr<nsIURI> uri;
-  nsresult rv = aPrincipal->GetURI(getter_AddRefs(uri));
-  NS_ENSURE_SUCCESS(rv, false);
-
-  bool hasFlags;
-
-  // Allow access to uris that cannot be loaded by web content.
-  rv = NS_URIChainHasFlags(uri, nsIProtocolHandler::URI_DANGEROUS_TO_LOAD,
-                           &hasFlags);
-  NS_ENSURE_SUCCESS(rv, false);
-  if (hasFlags) {
-    return true;
-  }
-
-  // UI resources also get access.
-  rv = NS_URIChainHasFlags(uri, nsIProtocolHandler::URI_IS_UI_RESOURCE,
-                           &hasFlags);
-  NS_ENSURE_SUCCESS(rv, false);
-  if (hasFlags) {
-    return true;
-  }
-
-  auto principal = BasePrincipal::Cast(aPrincipal);
-  auto policy = principal->AddonPolicy();
-  return (policy && policy->IsPrivileged());
-}
-
 // static
 void nsContentUtils::Shutdown() {
   sInitialized = false;
@@ -3363,7 +3325,7 @@ nsresult nsContentUtils::LoadImage(
     nsIReferrerInfo* aReferrerInfo, imgINotificationObserver* aObserver,
     int32_t aLoadFlags, const nsAString& initiatorType,
     imgRequestProxy** aRequest, uint32_t aContentPolicyType,
-    bool aUseUrgentStartForChannel) {
+    bool aUseUrgentStartForChannel, bool aLinkPreload) {
   MOZ_ASSERT(aURI, "Must have a URI");
   MOZ_ASSERT(aContext, "Must have a context");
   MOZ_ASSERT(aLoadingDocument, "Must have a document");
@@ -3399,6 +3361,7 @@ nsresult nsContentUtils::LoadImage(
                               aContentPolicyType, /* content policy type */
                               initiatorType,      /* the load initiator */
                               aUseUrgentStartForChannel, /* urgent-start flag */
+                              aLinkPreload, /* <link preload> initiator */
                               aRequest);
 }
 
@@ -5845,26 +5808,6 @@ SameOriginCheckerImpl::GetInterface(const nsIID& aIID, void** aResult) {
   return QueryInterface(aIID, aResult);
 }
 
-/* static */
-nsresult nsContentUtils::GetASCIIOrigin(nsIPrincipal* aPrincipal,
-                                        nsACString& aOrigin) {
-  MOZ_ASSERT(aPrincipal, "missing principal");
-
-  aOrigin.Truncate();
-
-  nsCOMPtr<nsIURI> uri;
-  nsresult rv = aPrincipal->GetURI(getter_AddRefs(uri));
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  if (uri) {
-    return GetASCIIOrigin(uri, aOrigin);
-  }
-
-  aOrigin.AssignLiteral("null");
-
-  return NS_OK;
-}
-
 /* static */
 nsresult nsContentUtils::GetASCIIOrigin(nsIURI* aURI, nsACString& aOrigin) {
   MOZ_ASSERT(aURI, "missing uri");
@@ -5922,8 +5865,10 @@ nsresult nsContentUtils::GetUTFOrigin(nsIPrincipal* aPrincipal,
   aOrigin.Truncate();
   nsAutoCString asciiOrigin;
 
-  nsresult rv = GetASCIIOrigin(aPrincipal, asciiOrigin);
-  NS_ENSURE_SUCCESS(rv, rv);
+  nsresult rv = aPrincipal->GetAsciiOrigin(asciiOrigin);
+  if (NS_FAILED(rv)) {
+    asciiOrigin.AssignLiteral("null");
+  }
 
   aOrigin = NS_ConvertUTF8toUTF16(asciiOrigin);
   return NS_OK;
@@ -8020,7 +7965,8 @@ bool nsContentUtils::IsPreloadType(nsContentPolicyType aType) {
   return (aType == nsIContentPolicy::TYPE_INTERNAL_SCRIPT_PRELOAD ||
           aType == nsIContentPolicy::TYPE_INTERNAL_MODULE_PRELOAD ||
           aType == nsIContentPolicy::TYPE_INTERNAL_IMAGE_PRELOAD ||
-          aType == nsIContentPolicy::TYPE_INTERNAL_STYLESHEET_PRELOAD);
+          aType == nsIContentPolicy::TYPE_INTERNAL_STYLESHEET_PRELOAD ||
+          aType == nsIContentPolicy::TYPE_INTERNAL_FONT_PRELOAD);
 }
 
 /* static */
@@ -8330,7 +8276,8 @@ class StringBuilder {
       return false;
     }
 
-    for (StringBuilder* current = this; current; current = current->mNext) {
+    for (StringBuilder* current = this; current;
+         current = current->mNext.get()) {
       uint32_t len = current->mUnits.Length();
       for (uint32_t i = 0; i < len; ++i) {
         Unit& u = current->mUnits[i];
@@ -8386,7 +8333,7 @@ class StringBuilder {
 
   explicit StringBuilder(StringBuilder* aFirst) : mLast(nullptr), mLength(0) {
     MOZ_COUNT_CTOR(StringBuilder);
-    aFirst->mLast->mNext = this;
+    aFirst->mLast->mNext = WrapUnique(this);
     aFirst->mLast = this;
   }
 
@@ -8457,7 +8404,7 @@ class StringBuilder {
   }
 
   AutoTArray<Unit, STRING_BUFFER_UNITS> mUnits;
-  nsAutoPtr<StringBuilder> mNext;
+  mozilla::UniquePtr<StringBuilder> mNext;
   StringBuilder* mLast;
   // mLength is used only in the first StringBuilder object in the linked list.
   CheckedInt<uint32_t> mLength;
@@ -8806,20 +8753,15 @@ bool nsContentUtils::IsSpecificAboutPage(JSObject* aGlobal, const char* aUri) {
 
   nsCOMPtr<nsIPrincipal> principal = win->GetPrincipal();
   NS_ENSURE_TRUE(principal, false);
-  nsCOMPtr<nsIURI> uri;
-  principal->GetURI(getter_AddRefs(uri));
-  if (!uri) {
-    return false;
-  }
 
   // First check the scheme to avoid getting long specs in the common case.
   if (!principal->SchemeIs("about")) {
     return false;
   }
 
-  // Now check the spec itself
   nsAutoCString spec;
-  uri->GetSpecIgnoringRef(spec);
+  principal->GetAsciiSpec(spec);
+
   return spec.EqualsASCII(aUri);
 }
 
diff --git a/dom/base/nsContentUtils.h b/dom/base/nsContentUtils.h
index 66d47204c7..e062f94d8d 100644
--- a/dom/base/nsContentUtils.h
+++ b/dom/base/nsContentUtils.h
@@ -235,6 +235,7 @@ class nsContentUtils {
 #else
       ;
 #endif
+  static bool IsErrorPage(nsIURI* aURI);
 
   static bool IsCallerChromeOrFuzzingEnabled(JSContext* aCx, JSObject*) {
     return ThreadsafeIsSystemCaller(aCx) || IsFuzzingEnabled();
@@ -905,7 +906,7 @@ class nsContentUtils {
       int32_t aLoadFlags, const nsAString& initiatorType,
       imgRequestProxy** aRequest,
       uint32_t aContentPolicyType = nsIContentPolicy::TYPE_INTERNAL_IMAGE,
-      bool aUseUrgentStartForChannel = false);
+      bool aUseUrgentStartForChannel = false, bool aLinkPreload = false);
 
   /**
    * Obtain an image loader that respects the given document/channel's privacy
@@ -2195,7 +2196,6 @@ class nsContentUtils {
    *
    * @note this should be used for HTML5 origin determination.
    */
-  static nsresult GetASCIIOrigin(nsIPrincipal* aPrincipal, nsACString& aOrigin);
   static nsresult GetASCIIOrigin(nsIURI* aURI, nsACString& aOrigin);
   static nsresult GetUTFOrigin(nsIPrincipal* aPrincipal, nsAString& aOrigin);
   static nsresult GetUTFOrigin(nsIURI* aURI, nsAString& aOrigin);
@@ -3351,6 +3351,8 @@ nsContentUtils::InternalContentPolicyTypeToExternal(nsContentPolicyType aType) {
     case nsIContentPolicy::TYPE_INTERNAL_SHARED_WORKER:
     case nsIContentPolicy::TYPE_INTERNAL_SERVICE_WORKER:
     case nsIContentPolicy::TYPE_INTERNAL_WORKER_IMPORT_SCRIPTS:
+    case nsIContentPolicy::TYPE_INTERNAL_AUDIOWORKLET:
+    case nsIContentPolicy::TYPE_INTERNAL_PAINTWORKLET:
       return nsIContentPolicy::TYPE_SCRIPT;
 
     case nsIContentPolicy::TYPE_INTERNAL_EMBED:
@@ -3383,6 +3385,9 @@ nsContentUtils::InternalContentPolicyTypeToExternal(nsContentPolicyType aType) {
     case nsIContentPolicy::TYPE_INTERNAL_FORCE_ALLOWED_DTD:
       return nsIContentPolicy::TYPE_DTD;
 
+    case nsIContentPolicy::TYPE_INTERNAL_FONT_PRELOAD:
+      return nsIContentPolicy::TYPE_FONT;
+
     default:
       return aType;
   }
diff --git a/dom/base/nsDOMDataChannel.cpp b/dom/base/nsDOMDataChannel.cpp
index d26b37123c..f9a4f06c13 100644
--- a/dom/base/nsDOMDataChannel.cpp
+++ b/dom/base/nsDOMDataChannel.cpp
@@ -25,10 +25,6 @@
 #include "DataChannel.h"
 #include "DataChannelLog.h"
 
-#undef LOG
-#define LOG(args) \
-  MOZ_LOG(mozilla::gDataChannelLog, mozilla::LogLevel::Debug, args)
-
 // Since we've moved the windows.h include down here, we have to explicitly
 // undef GetBinaryType, otherwise we'll get really odd conflicts
 #ifdef GetBinaryType
@@ -42,7 +38,7 @@ nsDOMDataChannel::~nsDOMDataChannel() {
   // Don't call us anymore!  Likely isn't an issue (or maybe just less of
   // one) once we block GC until all the (appropriate) onXxxx handlers
   // are dropped. (See WebRTC spec)
-  LOG(("%p: Close()ing %p", this, mDataChannel.get()));
+  DC_DEBUG(("%p: Close()ing %p", this, mDataChannel.get()));
   mDataChannel->SetListener(nullptr, nullptr);
   mDataChannel->Close();
 }
@@ -103,8 +99,8 @@ nsresult nsDOMDataChannel::Init(nsPIDOMWindowInner* aDOMWindow) {
   NS_ENSURE_SUCCESS(rv, rv);
 
   rv = nsContentUtils::GetUTFOrigin(principal, mOrigin);
-  LOG(("%s: origin = %s\n", __FUNCTION__,
-       NS_LossyConvertUTF16toASCII(mOrigin).get()));
+  DC_DEBUG(("%s: origin = %s\n", __FUNCTION__,
+            NS_LossyConvertUTF16toASCII(mOrigin).get()));
   return rv;
 }
 
@@ -265,10 +261,10 @@ nsresult nsDOMDataChannel::DoOnMessageAvailable(const nsACString& aData,
                                                 bool aBinary) {
   MOZ_ASSERT(NS_IsMainThread());
 
-  LOG(("DoOnMessageAvailable%s\n",
-       aBinary
-           ? ((mBinaryType == DC_BINARY_TYPE_BLOB) ? " (blob)" : " (binary)")
-           : ""));
+  DC_VERBOSE((
+      "DoOnMessageAvailable%s\n",
+      aBinary ? ((mBinaryType == DC_BINARY_TYPE_BLOB) ? " (blob)" : " (binary)")
+              : ""));
 
   nsresult rv = CheckCurrentGlobalCorrectness();
   if (NS_FAILED(rv)) {
@@ -319,10 +315,13 @@ nsresult nsDOMDataChannel::DoOnMessageAvailable(const nsACString& aData,
                           nullptr, Sequence<OwningNonNull<MessagePort>>());
   event->SetTrusted(true);
 
-  LOG(("%p(%p): %s - Dispatching\n", this, (void*)mDataChannel, __FUNCTION__));
+  DC_DEBUG(
+      ("%p(%p): %s - Dispatching\n", this, (void*)mDataChannel, __FUNCTION__));
   ErrorResult err;
   DispatchEvent(*event, err);
   if (err.Failed()) {
+    DC_ERROR(("%p(%p): %s - Failed to dispatch message", this,
+              (void*)mDataChannel, __FUNCTION__));
     NS_WARNING("Failed to dispatch the message event!!!");
   }
   return err.StealNSResult();
@@ -360,7 +359,8 @@ nsresult nsDOMDataChannel::OnSimpleEvent(nsISupports* aContext,
 }
 
 nsresult nsDOMDataChannel::OnChannelConnected(nsISupports* aContext) {
-  LOG(("%p(%p): %s - Dispatching\n", this, (void*)mDataChannel, __FUNCTION__));
+  DC_DEBUG(
+      ("%p(%p): %s - Dispatching\n", this, (void*)mDataChannel, __FUNCTION__));
 
   return OnSimpleEvent(aContext, NS_LITERAL_STRING("open"));
 }
@@ -372,8 +372,8 @@ nsresult nsDOMDataChannel::OnChannelClosed(nsISupports* aContext) {
   if (!mSentClose) {
     // Ok, we're done with it.
     mDataChannel->ReleaseConnection();
-    LOG(("%p(%p): %s - Dispatching\n", this, (void*)mDataChannel,
-         __FUNCTION__));
+    DC_DEBUG(("%p(%p): %s - Dispatching\n", this, (void*)mDataChannel,
+              __FUNCTION__));
 
     rv = OnSimpleEvent(aContext, NS_LITERAL_STRING("close"));
     // no more events can happen
@@ -386,7 +386,8 @@ nsresult nsDOMDataChannel::OnChannelClosed(nsISupports* aContext) {
 }
 
 nsresult nsDOMDataChannel::OnBufferLow(nsISupports* aContext) {
-  LOG(("%p(%p): %s - Dispatching\n", this, (void*)mDataChannel, __FUNCTION__));
+  DC_DEBUG(
+      ("%p(%p): %s - Dispatching\n", this, (void*)mDataChannel, __FUNCTION__));
 
   return OnSimpleEvent(aContext, NS_LITERAL_STRING("bufferedamountlow"));
 }
diff --git a/dom/base/nsDOMMutationObserver.h b/dom/base/nsDOMMutationObserver.h
index 529e5d5972..5b2fc51c20 100644
--- a/dom/base/nsDOMMutationObserver.h
+++ b/dom/base/nsDOMMutationObserver.h
@@ -5,26 +5,27 @@
 #ifndef nsDOMMutationObserver_h
 #define nsDOMMutationObserver_h
 
+#include <utility>
+
 #include "mozilla/Attributes.h"
-#include "mozilla/Move.h"
+#include "mozilla/dom/Animation.h"
+#include "mozilla/dom/Document.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/dom/MutationEventBinding.h"
+#include "mozilla/dom/MutationObserverBinding.h"
+#include "mozilla/dom/Nullable.h"
+#include "nsCOMArray.h"
+#include "nsClassHashtable.h"
+#include "nsContentList.h"
 #include "nsCycleCollectionParticipant.h"
-#include "nsPIDOMWindow.h"
+#include "nsGlobalWindow.h"
+#include "nsIAnimationObserver.h"
 #include "nsIScriptContext.h"
+#include "nsIVariant.h"
+#include "nsPIDOMWindow.h"
 #include "nsStubAnimationObserver.h"
-#include "nsCOMArray.h"
 #include "nsTArray.h"
-#include "nsIVariant.h"
-#include "nsContentList.h"
-#include "mozilla/dom/Element.h"
-#include "nsClassHashtable.h"
 #include "nsWrapperCache.h"
-#include "mozilla/dom/Nullable.h"
-#include "mozilla/dom/MutationEventBinding.h"
-#include "mozilla/dom/MutationObserverBinding.h"
-#include "mozilla/dom/Document.h"
-#include "mozilla/dom/Animation.h"
-#include "nsIAnimationObserver.h"
-#include "nsGlobalWindow.h"
 
 class nsDOMMutationObserver;
 using mozilla::dom::MutationObservingInfo;
diff --git a/dom/base/nsDocumentEncoder.cpp b/dom/base/nsDocumentEncoder.cpp
index 02431a53df..876c944f28 100644
--- a/dom/base/nsDocumentEncoder.cpp
+++ b/dom/base/nsDocumentEncoder.cpp
@@ -15,8 +15,10 @@
 #include "nsISupports.h"
 #include "mozilla/dom/Document.h"
 #include "nsCOMPtr.h"
+#include "nsCRT.h"
 #include "nsIContentSerializer.h"
 #include "mozilla/Encoding.h"
+#include "nsComponentManagerUtils.h"
 #include "nsIOutputStream.h"
 #include "nsRange.h"
 #include "nsGkAtoms.h"
@@ -24,6 +26,7 @@
 #include "nsIContent.h"
 #include "nsIScriptContext.h"
 #include "nsIScriptGlobalObject.h"
+#include "nsITransferable.h"
 #include "mozilla/dom/Selection.h"
 #include "nsContentUtils.h"
 #include "nsElementTable.h"
diff --git a/dom/base/nsFrameMessageManager.cpp b/dom/base/nsFrameMessageManager.cpp
index f416c720ee..efcefa36e8 100644
--- a/dom/base/nsFrameMessageManager.cpp
+++ b/dom/base/nsFrameMessageManager.cpp
@@ -85,7 +85,7 @@ nsFrameMessageManager::nsFrameMessageManager(MessageManagerCallback* aCallback,
   NS_ASSERTION(!mIsBroadcaster || !mCallback,
                "Broadcasters cannot have callbacks!");
   if (mOwnsCallback) {
-    mOwnedCallback = aCallback;
+    mOwnedCallback = WrapUnique(aCallback);
   }
 }
 
@@ -439,17 +439,7 @@ static bool AllowMessage(size_t aDataLength, const nsAString& aMessageName) {
   // result in an overly large IPC message.
   static const size_t kMaxMessageSize =
       IPC::Channel::kMaximumMessageSize - 20 * 1024;
-  if (aDataLength < kMaxMessageSize) {
-    return true;
-  }
-
-  NS_ConvertUTF16toUTF8 messageName(aMessageName);
-  messageName.StripTaggedASCII(ASCIIMask::Mask0to9());
-
-  Telemetry::Accumulate(Telemetry::REJECTED_MESSAGE_MANAGER_MESSAGE,
-                        messageName);
-
-  return false;
+  return aDataLength < kMaxMessageSize;
 }
 
 void nsFrameMessageManager::SendMessage(
@@ -845,7 +835,7 @@ void nsFrameMessageManager::SetCallback(MessageManagerCallback* aCallback) {
   if (aCallback && mCallback != aCallback) {
     mCallback = aCallback;
     if (mOwnsCallback) {
-      mOwnedCallback = aCallback;
+      mOwnedCallback = WrapUnique(aCallback);
     }
   }
 }
diff --git a/dom/base/nsFrameMessageManager.h b/dom/base/nsFrameMessageManager.h
index 5d37f8b7ce..70b62f4617 100644
--- a/dom/base/nsFrameMessageManager.h
+++ b/dom/base/nsFrameMessageManager.h
@@ -8,7 +8,6 @@
 #include "nsIMessageManager.h"
 #include "nsIObserver.h"
 #include "nsCOMPtr.h"
-#include "nsAutoPtr.h"
 #include "nsCOMArray.h"
 #include "nsTArray.h"
 #include "nsAtom.h"
@@ -26,6 +25,7 @@
 #include "js/RootingAPI.h"
 #include "nsTObserverArray.h"
 #include "mozilla/TypedEnumBits.h"
+#include "mozilla/UniquePtr.h"
 #include "mozilla/dom/CallbackObject.h"
 #include "mozilla/dom/SameProcessMessageQueue.h"
 #include "mozilla/dom/ipc/StructuredCloneData.h"
@@ -332,7 +332,7 @@ class nsFrameMessageManager : public nsIMessageSender {
   bool mClosed;  // true if we can no longer send messages
   bool mDisconnected;
   mozilla::dom::ipc::MessageManagerCallback* mCallback;
-  nsAutoPtr<mozilla::dom::ipc::MessageManagerCallback> mOwnedCallback;
+  mozilla::UniquePtr<mozilla::dom::ipc::MessageManagerCallback> mOwnedCallback;
   nsTArray<nsString> mPendingScripts;
   nsTArray<bool> mPendingScriptsGlobalStates;
   JS::Heap<JS::Value> mInitialProcessData;
diff --git a/dom/base/nsGlobalWindowInner.cpp b/dom/base/nsGlobalWindowInner.cpp
index 754daa71e0..164e74e9f1 100644
--- a/dom/base/nsGlobalWindowInner.cpp
+++ b/dom/base/nsGlobalWindowInner.cpp
@@ -2927,13 +2927,6 @@ bool nsGlobalWindowInner::IsPrivilegedChromeWindow(JSContext* aCx,
              nsContentUtils::GetSystemPrincipal();
 }
 
-/* static */
-bool nsGlobalWindowInner::OfflineCacheAllowedForContext(JSContext* aCx,
-                                                        JSObject* aObj) {
-  return IsSecureContextOrObjectIsFromSecureContext(aCx, aObj) ||
-         Preferences::GetBool("browser.cache.offline.insecure.enable");
-}
-
 /* static */
 bool nsGlobalWindowInner::IsRequestIdleCallbackEnabled(JSContext* aCx,
                                                        JSObject* aObj) {
diff --git a/dom/base/nsGlobalWindowInner.h b/dom/base/nsGlobalWindowInner.h
index 36efe4a640..0556328dd8 100644
--- a/dom/base/nsGlobalWindowInner.h
+++ b/dom/base/nsGlobalWindowInner.h
@@ -14,7 +14,6 @@
 // Local Includes
 // Helper Classes
 #include "nsCOMPtr.h"
-#include "nsAutoPtr.h"
 #include "nsWeakReference.h"
 #include "nsDataHashtable.h"
 #include "nsJSThingHashtable.h"
@@ -393,9 +392,6 @@ class nsGlobalWindowInner final : public mozilla::dom::EventTarget,
 
   static bool IsPrivilegedChromeWindow(JSContext* /* unused */, JSObject* aObj);
 
-  static bool OfflineCacheAllowedForContext(JSContext* /* unused */,
-                                            JSObject* aObj);
-
   static bool IsRequestIdleCallbackEnabled(JSContext* aCx,
                                            JSObject* /* unused */);
 
diff --git a/dom/base/nsGlobalWindowOuter.cpp b/dom/base/nsGlobalWindowOuter.cpp
index 69db071b8c..574b67cee1 100644
--- a/dom/base/nsGlobalWindowOuter.cpp
+++ b/dom/base/nsGlobalWindowOuter.cpp
@@ -5551,7 +5551,7 @@ bool nsGlobalWindowOuter::SameLoadingURI(Document* aDoc, nsIChannel* aChannel) {
   }
   nsCOMPtr<nsILoadInfo> channelLoadInfo = aChannel->LoadInfo();
   nsCOMPtr<nsIPrincipal> channelLoadingPrincipal =
-      channelLoadInfo->LoadingPrincipal();
+      channelLoadInfo->GetLoadingPrincipal();
   if (!channelLoadingPrincipal) {
     // TYPE_DOCUMENT loads will not have a channelLoadingPrincipal. But top
     // level loads should not be blocked by Tracking Protection, so we will
diff --git a/dom/base/nsGlobalWindowOuter.h b/dom/base/nsGlobalWindowOuter.h
index 9fa6db3c25..c8f405bdab 100644
--- a/dom/base/nsGlobalWindowOuter.h
+++ b/dom/base/nsGlobalWindowOuter.h
@@ -15,7 +15,6 @@
 // Local Includes
 // Helper Classes
 #include "nsCOMPtr.h"
-#include "nsAutoPtr.h"
 #include "nsWeakReference.h"
 #include "nsDataHashtable.h"
 #include "nsJSThingHashtable.h"
diff --git a/dom/base/nsIContentPolicy.idl b/dom/base/nsIContentPolicy.idl
index e41d7870f2..414f21a6b4 100644
--- a/dom/base/nsIContentPolicy.idl
+++ b/dom/base/nsIContentPolicy.idl
@@ -374,6 +374,30 @@ interface nsIContentPolicy : nsISupports
    */
   const nsContentPolicyType TYPE_INTERNAL_FORCE_ALLOWED_DTD = 48;
 
+  /**
+   * Indicates an internal constant for scripts loaded through an
+   * audioWorklet.
+   *
+   * This will be mapped to TYPE_SCRIPT before being passed to content policy
+   * implementations.
+   */
+  const nsContentPolicyType TYPE_INTERNAL_AUDIOWORKLET = 49;
+
+  /**
+   * Indicates an internal constant for scripts loaded through an
+   * paintWorklet.
+   *
+   * This will be mapped to TYPE_SCRIPT before being passed to content policy
+   * implementations.
+   */
+  const nsContentPolicyType TYPE_INTERNAL_PAINTWORKLET = 50;
+
+  /**
+   * Same as TYPE_FONT but indicates this is a <link rel=preload as=font>
+   * preload initiated load.
+   */
+  const nsContentPolicyType TYPE_INTERNAL_FONT_PRELOAD = 51;
+
   /* When adding new content types, please update nsContentBlocker,
    * NS_CP_ContentTypeName, nsCSPContext, CSP_ContentTypeToDirective,
    * DoContentSecurityChecks, all nsIContentPolicy implementations, the
diff --git a/dom/base/nsINode.cpp b/dom/base/nsINode.cpp
index ad7b067789..b12c1236d6 100644
--- a/dom/base/nsINode.cpp
+++ b/dom/base/nsINode.cpp
@@ -1990,10 +1990,9 @@ static bool MatchAttribute(Element* aElement, int32_t aNamespaceID,
 already_AddRefed<nsIHTMLCollection> nsINode::GetElementsByAttribute(
     const nsAString& aAttribute, const nsAString& aValue) {
   RefPtr<nsAtom> attrAtom(NS_Atomize(aAttribute));
-  nsAutoPtr<nsString> attrValue(new nsString(aValue));
   RefPtr<nsContentList> list = new nsContentList(
       this, MatchAttribute, nsContentUtils::DestroyMatchString,
-      attrValue.forget(), true, attrAtom, kNameSpaceID_Unknown);
+      new nsString(aValue), true, attrAtom, kNameSpaceID_Unknown);
 
   return list.forget();
 }
@@ -2002,7 +2001,6 @@ already_AddRefed<nsIHTMLCollection> nsINode::GetElementsByAttributeNS(
     const nsAString& aNamespaceURI, const nsAString& aAttribute,
     const nsAString& aValue, ErrorResult& aRv) {
   RefPtr<nsAtom> attrAtom(NS_Atomize(aAttribute));
-  nsAutoPtr<nsString> attrValue(new nsString(aValue));
 
   int32_t nameSpaceId = kNameSpaceID_Wildcard;
   if (!aNamespaceURI.EqualsLiteral("*")) {
@@ -2016,7 +2014,7 @@ already_AddRefed<nsIHTMLCollection> nsINode::GetElementsByAttributeNS(
 
   RefPtr<nsContentList> list = new nsContentList(
       this, MatchAttribute, nsContentUtils::DestroyMatchString,
-      attrValue.forget(), true, attrAtom, nameSpaceId);
+      new nsString(aValue), true, attrAtom, nameSpaceId);
   return list.forget();
 }
 
diff --git a/dom/base/nsINode.h b/dom/base/nsINode.h
index 684d7337c6..9c6da51bdb 100644
--- a/dom/base/nsINode.h
+++ b/dom/base/nsINode.h
@@ -90,6 +90,7 @@ template <typename T>
 class InclusiveAncestorsOfTypeIterator;
 template <typename T>
 class InclusiveFlatTreeAncestorsOfTypeIterator;
+class LinkStyle;
 class MutationObservers;
 template <typename T>
 class Optional;
@@ -519,6 +520,13 @@ class nsINode : public mozilla::dom::EventTarget {
 
   virtual bool IsTextControlElement() const { return false; }
 
+  // Returns non-null if this element subclasses `LinkStyle`.
+  virtual const mozilla::dom::LinkStyle* AsLinkStyle() const { return nullptr; }
+  mozilla::dom::LinkStyle* AsLinkStyle() {
+    return const_cast<mozilla::dom::LinkStyle*>(
+        static_cast<const nsINode*>(this)->AsLinkStyle());
+  }
+
   /**
    * Return this node as an Element.  Should only be used for nodes
    * for which IsElement() is true.  This is defined inline in Element.h.
diff --git a/dom/base/nsIStyleSheetLinkingElement.h b/dom/base/nsIStyleSheetLinkingElement.h
deleted file mode 100644
index a7097a56de..0000000000
--- a/dom/base/nsIStyleSheetLinkingElement.h
+++ /dev/null
@@ -1,204 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-#ifndef nsIStyleSheetLinkingElement_h__
-#define nsIStyleSheetLinkingElement_h__
-
-#include "nsISupports.h"
-#include "mozilla/StyleSheet.h"
-#include "mozilla/Result.h"
-
-class nsIContent;
-class nsICSSLoaderObserver;
-class nsIPrincipal;
-class nsIURI;
-
-#define NS_ISTYLESHEETLINKINGELEMENT_IID             \
-  {                                                  \
-    0xa8b79f3b, 0x9d18, 0x4f9c, {                    \
-      0xb1, 0xaa, 0x8c, 0x9b, 0x1b, 0xaa, 0xac, 0xad \
-    }                                                \
-  }
-
-class nsIStyleSheetLinkingElement : public nsISupports {
- public:
-  enum class ForceUpdate : uint8_t {
-    No,
-    Yes,
-  };
-
-  enum class Completed : uint8_t {
-    No,
-    Yes,
-  };
-
-  enum class HasAlternateRel : uint8_t {
-    No,
-    Yes,
-  };
-
-  enum class IsAlternate : uint8_t {
-    No,
-    Yes,
-  };
-
-  enum class IsInline : uint8_t {
-    No,
-    Yes,
-  };
-
-  enum class IsExplicitlyEnabled : uint8_t {
-    No,
-    Yes,
-  };
-
-  enum class MediaMatched : uint8_t {
-    Yes,
-    No,
-  };
-
-  struct Update {
-   private:
-    bool mWillNotify;
-    bool mIsAlternate;
-    bool mMediaMatched;
-
-   public:
-    Update() : mWillNotify(false), mIsAlternate(false), mMediaMatched(false) {}
-
-    Update(Completed aCompleted, IsAlternate aIsAlternate,
-           MediaMatched aMediaMatched)
-        : mWillNotify(aCompleted == Completed::No),
-          mIsAlternate(aIsAlternate == IsAlternate::Yes),
-          mMediaMatched(aMediaMatched == MediaMatched::Yes) {}
-
-    bool WillNotify() const { return mWillNotify; }
-
-    bool ShouldBlock() const {
-      if (!mWillNotify) {
-        return false;
-      }
-
-      return !mIsAlternate && mMediaMatched;
-    }
-  };
-
-  struct MOZ_STACK_CLASS SheetInfo {
-    nsIContent* mContent;
-    // FIXME(emilio): do these really need to be strong refs?
-    nsCOMPtr<nsIURI> mURI;
-
-    // The principal of the scripted caller that initiated the load, if
-    // available. Otherwise null.
-    nsCOMPtr<nsIPrincipal> mTriggeringPrincipal;
-    nsCOMPtr<nsIReferrerInfo> mReferrerInfo;
-    mozilla::CORSMode mCORSMode;
-    nsString mTitle;
-    nsString mMedia;
-    nsString mIntegrity;
-    nsString mNonce;
-
-    bool mHasAlternateRel;
-    bool mIsInline;
-    IsExplicitlyEnabled mIsExplicitlyEnabled;
-
-    SheetInfo(const mozilla::dom::Document&, nsIContent*,
-              already_AddRefed<nsIURI> aURI,
-              already_AddRefed<nsIPrincipal> aTriggeringPrincipal,
-              already_AddRefed<nsIReferrerInfo> aReferrerInfo,
-              mozilla::CORSMode, const nsAString& aTitle,
-              const nsAString& aMedia,
-              const nsAString& aIntegrity,
-              const nsAString& aNonce,
-              HasAlternateRel, IsInline,
-              IsExplicitlyEnabled);
-
-    ~SheetInfo();
-  };
-
-  NS_DECLARE_STATIC_IID_ACCESSOR(NS_ISTYLESHEETLINKINGELEMENT_IID)
-
-  /**
-   * Used to make the association between a style sheet and
-   * the element that linked it to the document.
-   *
-   * @param aStyleSheet the style sheet associated with this
-   *                    element.
-   */
-  virtual void SetStyleSheet(mozilla::StyleSheet* aStyleSheet) = 0;
-
-
-  /**
-   * Initialize the stylesheet linking element. If aDontLoadStyle is
-   * true the element will ignore the first modification to the
-   * element that would cause a stylesheet to be loaded. Subsequent
-   * modifications to the element will not be ignored.
-   */
-  virtual void InitStyleLinkElement(bool aDontLoadStyle) = 0;
-
-  /**
-   * Tells this element to update the stylesheet.
-   *
-   * @param aObserver    observer to notify once the stylesheet is loaded.
-   *                     This will be passed to the CSSLoader
-   */
-  virtual mozilla::Result<Update, nsresult> UpdateStyleSheet(
-      nsICSSLoaderObserver* aObserver) = 0;
-
-  /**
-   * Tells this element whether to update the stylesheet when the
-   * element's properties change.
-   *
-   * @param aEnableUpdates update on changes or not.
-   */
-  virtual void SetEnableUpdates(bool aEnableUpdates) = 0;
-
-  /**
-   * Gets the charset that the element claims the style sheet is in.
-   * Can return empty string to indicate that we have no charset
-   * information.
-   *
-   * @param aCharset the charset
-   */
-  virtual void GetCharset(nsAString& aCharset) = 0;
-
-  /**
-   * Tells this element to use a different base URI. This is used for
-   * proper loading of xml-stylesheet processing instructions in XUL overlays
-   * and is only currently used by nsXMLStylesheetPI.
-   *
-   * @param aNewBaseURI the new base URI, nullptr to use the default base URI.
-   */
-  virtual void OverrideBaseURI(nsIURI* aNewBaseURI) = 0;
-
-  // This doesn't entirely belong here since they only make sense for
-  // some types of linking elements, but it's a better place than
-  // anywhere else.
-  virtual void SetLineNumber(uint32_t aLineNumber) = 0;
-
-  /**
-   * Get the line number, as previously set by SetLineNumber.
-   *
-   * @return the line number of this element; or 1 if no line number
-   *         was set
-   */
-  virtual uint32_t GetLineNumber() = 0;
-
-  // This doesn't entirely belong here since they only make sense for
-  // some types of linking elements, but it's a better place than
-  // anywhere else.
-  virtual void SetColumnNumber(uint32_t aColumnNumber) = 0;
-
-  /**
-   * Get the column number, as previously set by SetColumnNumber.
-   *
-   * @return the column number of this element; or 1 if no column number
-   *         was set
-   */
-  virtual uint32_t GetColumnNumber() = 0;
-};
-
-NS_DEFINE_STATIC_IID_ACCESSOR(nsIStyleSheetLinkingElement,
-                              NS_ISTYLESHEETLINKINGELEMENT_IID)
-
-#endif  // nsILinkingElement_h__
diff --git a/dom/base/nsImageLoadingContent.cpp b/dom/base/nsImageLoadingContent.cpp
index 55815dd6c7..f18671bc07 100644
--- a/dom/base/nsImageLoadingContent.cpp
+++ b/dom/base/nsImageLoadingContent.cpp
@@ -960,8 +960,8 @@ nsImageLoadingContent::LoadImageWithChannel(nsIChannel* aChannel,
 
   // Do the load.
   RefPtr<imgRequestProxy>& req = PrepareNextRequest(eImageLoadType_Normal);
-  nsresult rv = loader->LoadImageWithChannel(aChannel, this, ToSupports(doc),
-                                             aListener, getter_AddRefs(req));
+  nsresult rv = loader->LoadImageWithChannel(aChannel, this, doc, aListener,
+                                             getter_AddRefs(req));
   if (NS_SUCCEEDED(rv)) {
     CloneScriptedRequests(req);
     TrackImage(req);
diff --git a/dom/base/nsNodeInfoManager.cpp b/dom/base/nsNodeInfoManager.cpp
index ac7faf3209..6e6699002b 100644
--- a/dom/base/nsNodeInfoManager.cpp
+++ b/dom/base/nsNodeInfoManager.cpp
@@ -394,7 +394,7 @@ bool nsNodeInfoManager::InternalSVGEnabled() {
              nsIContentPolicy::TYPE_IMAGE ||
          loadInfo->GetExternalContentPolicyType() ==
              nsIContentPolicy::TYPE_OTHER) &&
-        (IsSystemOrAddonPrincipal(loadInfo->LoadingPrincipal()) ||
+        (IsSystemOrAddonPrincipal(loadInfo->GetLoadingPrincipal()) ||
          IsSystemOrAddonPrincipal(loadInfo->TriggeringPrincipal()))));
   mSVGEnabled = Some(conclusion);
   return conclusion;
diff --git a/dom/base/nsObjectLoadingContent.cpp b/dom/base/nsObjectLoadingContent.cpp
index 31c12302ef..d18a154d8b 100644
--- a/dom/base/nsObjectLoadingContent.cpp
+++ b/dom/base/nsObjectLoadingContent.cpp
@@ -70,6 +70,7 @@
 #include "nsContentCID.h"
 #include "mozilla/BasicEvents.h"
 #include "mozilla/Components.h"
+#include "mozilla/LoadInfo.h"
 #include "mozilla/dom/BindingUtils.h"
 #include "mozilla/dom/Element.h"
 #include "mozilla/dom/Event.h"
@@ -85,6 +86,7 @@
 #include "mozilla/dom/HTMLEmbedElement.h"
 #include "mozilla/dom/HTMLObjectElement.h"
 #include "mozilla/dom/UserActivation.h"
+#include "mozilla/dom/nsCSPContext.h"
 #include "mozilla/net/UrlClassifierFeatureFactory.h"
 #include "mozilla/LoadInfo.h"
 #include "mozilla/PresShell.h"
@@ -2306,6 +2308,21 @@ nsresult nsObjectLoadingContent::OpenChannel() {
     loadinfo->SetPrincipalToInherit(thisContent->NodePrincipal());
   }
 
+  // For object loads we store the CSP that potentially needs to
+  // be inherited, e.g. in case we are loading an opaque origin
+  // like a data: URI. The actual inheritance check happens within
+  // Document::InitCSP(). Please create an actual copy of the CSP
+  // (do not share the same reference) otherwise a Meta CSP of an
+  // opaque origin will incorrectly be propagated to the embedding
+  // document.
+  nsCOMPtr<nsIContentSecurityPolicy> csp = doc->GetCsp();
+  if (csp) {
+    RefPtr<nsCSPContext> cspToInherit = new nsCSPContext();
+    cspToInherit->InitFromOther(static_cast<nsCSPContext*>(csp.get()));
+    nsCOMPtr<nsILoadInfo> loadinfo = chan->LoadInfo();
+    static_cast<LoadInfo*>(loadinfo.get())->SetCSPToInherit(cspToInherit);
+  }
+
   // Referrer
   nsCOMPtr<nsIHttpChannel> httpChan(do_QueryInterface(chan));
   if (httpChan) {
diff --git a/dom/base/nsQueryContentEventResult.cpp b/dom/base/nsQueryContentEventResult.cpp
index 11bb257a15..07a40344ab 100644
--- a/dom/base/nsQueryContentEventResult.cpp
+++ b/dom/base/nsQueryContentEventResult.cpp
@@ -2,11 +2,13 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-#include "nsIWidget.h"
-#include "nsPoint.h"
 #include "nsQueryContentEventResult.h"
-#include "mozilla/Move.h"
+
+#include <utility>
+
 #include "mozilla/TextEvents.h"
+#include "nsIWidget.h"
+#include "nsPoint.h"
 
 using namespace mozilla;
 
diff --git a/dom/base/nsStyleLinkElement.h b/dom/base/nsStyleLinkElement.h
deleted file mode 100644
index c076677992..0000000000
--- a/dom/base/nsStyleLinkElement.h
+++ /dev/null
@@ -1,139 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-/*
- * A base class which implements nsIStyleSheetLinkingElement and can
- * be subclassed by various content nodes that want to load
- * stylesheets (<style>, <link>, processing instructions, etc).
- */
-
-#ifndef nsStyleLinkElement_h___
-#define nsStyleLinkElement_h___
-
-#include "mozilla/Attributes.h"
-#include "mozilla/CORSMode.h"
-#include "mozilla/StyleSheetInlines.h"
-#include "mozilla/Unused.h"
-#include "nsCOMPtr.h"
-#include "nsIStyleSheetLinkingElement.h"
-#include "nsTArray.h"
-
-class nsIURI;
-
-namespace mozilla {
-class CSSStyleSheet;
-namespace dom {
-class Document;
-class ShadowRoot;
-}  // namespace dom
-}  // namespace mozilla
-
-class nsStyleLinkElement : public nsIStyleSheetLinkingElement {
- public:
-  nsStyleLinkElement();
-  virtual ~nsStyleLinkElement();
-
-  NS_IMETHOD QueryInterface(REFNSIID aIID, void** aInstancePtr) override = 0;
-
-  mozilla::StyleSheet* GetSheet() const { return mStyleSheet; }
-
-  // nsIStyleSheetLinkingElement
-  void SetStyleSheet(mozilla::StyleSheet* aStyleSheet) override;
-  void InitStyleLinkElement(bool aDontLoadStyle) override;
-
-  mozilla::Result<Update, nsresult> UpdateStyleSheet(
-      nsICSSLoaderObserver*) override;
-
-  void SetEnableUpdates(bool aEnableUpdates) override;
-  void GetCharset(nsAString& aCharset) override;
-
-  void OverrideBaseURI(nsIURI* aNewBaseURI) override;
-  void SetLineNumber(uint32_t aLineNumber) override;
-  uint32_t GetLineNumber() override;
-  void SetColumnNumber(uint32_t aColumnNumber) override;
-  uint32_t GetColumnNumber() override;
-
-  enum RelValue {
-    ePREFETCH = 0x00000001,
-    eDNS_PREFETCH = 0x00000002,
-    eSTYLESHEET = 0x00000004,
-    eNEXT = 0x00000008,
-    eALTERNATE = 0x00000010,
-    ePRECONNECT = 0x00000020,
-    // NOTE: 0x40 is unused
-    ePRELOAD = 0x00000080
-  };
-
-  // The return value is a bitwise or of 0 or more RelValues.
-  static uint32_t ParseLinkTypes(const nsAString& aTypes);
-
-  void UpdateStyleSheetInternal() {
-    mozilla::Unused << UpdateStyleSheetInternal(nullptr, nullptr);
-  }
-
- protected:
-  /**
-   * @param aOldDocument   should be non-null only if we're updating because we
-   *                       removed the node from the document.
-   * @param aOldShadowRoot should be non-null only if we're updating because we
-   *                       removed the node from a shadow tree.
-   * @param aForceUpdate true will force the update even if the URI has not
-   *                     changed.  This should be used in cases when something
-   *                     about the content that affects the resulting sheet
-   *                     changed but the URI may not have changed.
-   *
-   * TODO(emilio): Should probably pass a single DocumentOrShadowRoot.
-   */
-  mozilla::Result<Update, nsresult> UpdateStyleSheetInternal(
-      mozilla::dom::Document* aOldDocument,
-      mozilla::dom::ShadowRoot* aOldShadowRoot, ForceUpdate = ForceUpdate::No);
-
-  // Gets a suitable title and media for SheetInfo out of an element, which
-  // needs to be `this`.
-  //
-  // NOTE(emilio): Needs nsString instead of nsAString because of
-  // CompressWhitespace.
-  static void GetTitleAndMediaForElement(const mozilla::dom::Element&,
-                                         nsString& aTitle, nsString& aMedia);
-
-  // Returns whether the type attribute specifies the text/css type for style
-  // elements.
-  static bool IsCSSMimeTypeAttributeForStyleElement(
-      const mozilla::dom::Element&);
-
-  virtual mozilla::Maybe<SheetInfo> GetStyleSheetInfo() = 0;
-
-  // CC methods
-  void Unlink();
-  void Traverse(nsCycleCollectionTraversalCallback& cb);
-
- private:
-  /**
-   * @param aOldDocument should be non-null only if we're updating because we
-   *                     removed the node from the document.
-   * @param aOldShadowRoot The ShadowRoot that used to contain the style.
-   *                     Passed as a parameter because on an update, the node
-   *                     is removed from the tree before the sheet is removed
-   *                     from the ShadowRoot.
-   * @param aForceUpdate true will force the update even if the URI has not
-   *                     changed.  This should be used in cases when something
-   *                     about the content that affects the resulting sheet
-   *                     changed but the URI may not have changed.
-   */
-  mozilla::Result<Update, nsresult> DoUpdateStyleSheet(
-      mozilla::dom::Document* aOldDocument,
-      mozilla::dom::ShadowRoot* aOldShadowRoot, nsICSSLoaderObserver* aObserver,
-      ForceUpdate);
-
-  RefPtr<mozilla::StyleSheet> mStyleSheet;
-
- protected:
-  nsCOMPtr<nsIPrincipal> mTriggeringPrincipal;
-  bool mDontLoadStyle;
-  bool mUpdatesEnabled;
-  uint32_t mLineNumber;
-  uint32_t mColumnNumber;
-};
-
-#endif /* nsStyleLinkElement_h___ */
diff --git a/dom/base/nsTreeSanitizer.cpp b/dom/base/nsTreeSanitizer.cpp
index 189c043351..b37ae5ad3e 100644
--- a/dom/base/nsTreeSanitizer.cpp
+++ b/dom/base/nsTreeSanitizer.cpp
@@ -562,11 +562,12 @@ const nsStaticAtom* const kAttributesSVG[] = {
     nsGkAtoms::text_anchor,        // text-anchor
     nsGkAtoms::text_decoration,    // text-decoration
     // textLength
-    nsGkAtoms::text_rendering,  // text-rendering
-    nsGkAtoms::title,           // title
-    nsGkAtoms::to,              // to
-    nsGkAtoms::transform,       // transform
-    nsGkAtoms::type,            // type
+    nsGkAtoms::text_rendering,    // text-rendering
+    nsGkAtoms::title,             // title
+    nsGkAtoms::to,                // to
+    nsGkAtoms::transform,         // transform
+    nsGkAtoms::transform_origin,  // transform-origin
+    nsGkAtoms::type,              // type
     // u1
     // u2
     // underline-position
diff --git a/dom/bindings/Bindings.conf b/dom/bindings/Bindings.conf
index f821bd1f40..4a4df2f8d8 100644
--- a/dom/bindings/Bindings.conf
+++ b/dom/bindings/Bindings.conf
@@ -1341,6 +1341,7 @@ DOMInterfaces = {
 'Worklet': {
     # Paint worklets just use the Worklet interface.
     'concrete': True,
+    'implicitJSContext': [ 'addModule' ],
 },
 
 'XMLHttpRequest': {
diff --git a/dom/bindings/Codegen.py b/dom/bindings/Codegen.py
index 343be31385..289214485b 100644
--- a/dom/bindings/Codegen.py
+++ b/dom/bindings/Codegen.py
@@ -7498,7 +7498,9 @@ def getRetvalDeclarationForType(returnType, descriptorProvider,
             return CGGeneric("nsString"), "ref", None, None, None
         return CGGeneric("DOMString"), "ref", None, None, None
     if returnType.isByteString() or returnType.isUTF8String():
-        return CGGeneric("nsCString"), "ref", None, None, None
+        if isMember:
+            return CGGeneric("nsCString"), "ref", None, None, None
+        return CGGeneric("nsAutoCString"), "ref", None, None, None
     if returnType.isEnum():
         result = CGGeneric(returnType.unroll().inner.identifier.name)
         if returnType.nullable():
diff --git a/dom/bindings/Nullable.h b/dom/bindings/Nullable.h
index eadad8c3ef..6740ccacc3 100644
--- a/dom/bindings/Nullable.h
+++ b/dom/bindings/Nullable.h
@@ -5,12 +5,12 @@
 #ifndef mozilla_dom_Nullable_h
 #define mozilla_dom_Nullable_h
 
+#include <ostream>
+#include <utility>
+
 #include "mozilla/Assertions.h"
-#include "nsTArrayForwardDeclare.h"
-#include "mozilla/Move.h"
 #include "mozilla/Maybe.h"
-
-#include <ostream>
+#include "nsTArrayForwardDeclare.h"
 
 class nsCycleCollectionTraversalCallback;
 
diff --git a/dom/bindings/Record.h b/dom/bindings/Record.h
index a9a45af48e..965017aa57 100644
--- a/dom/bindings/Record.h
+++ b/dom/bindings/Record.h
@@ -9,12 +9,13 @@
 #ifndef mozilla_dom_Record_h
 #define mozilla_dom_Record_h
 
-#include "nsTHashtable.h"
+#include <utility>
+
+#include "mozilla/Attributes.h"
 #include "nsHashKeys.h"
 #include "nsString.h"
 #include "nsTArray.h"
-#include "mozilla/Attributes.h"
-#include "mozilla/Move.h"
+#include "nsTHashtable.h"
 
 namespace mozilla {
 namespace dom {
diff --git a/dom/bindings/ToJSValue.cpp b/dom/bindings/ToJSValue.cpp
index 063302ccb0..449ea58ad7 100644
--- a/dom/bindings/ToJSValue.cpp
+++ b/dom/bindings/ToJSValue.cpp
@@ -35,6 +35,11 @@ bool ToJSValue(JSContext* aCx, const nsAString& aArgument,
   return true;
 }
 
+bool ToJSValue(JSContext* aCx, const nsACString& aArgument,
+               JS::MutableHandle<JS::Value> aValue) {
+  return UTF8StringToJsval(aCx, aArgument, aValue);
+}
+
 bool ToJSValue(JSContext* aCx, nsresult aArgument,
                JS::MutableHandle<JS::Value> aValue) {
   RefPtr<Exception> exception = CreateException(aArgument);
@@ -91,5 +96,27 @@ bool ToJSValue(JSContext* aCx, const WindowProxyHolder& aArgument,
   return true;
 }
 
+// Static assertion tests for the `binding_detail::ScriptableInterfaceType`
+// helper template, used by `ToJSValue`.
+namespace binding_detail {
+static_assert(std::is_same_v<ScriptableInterfaceType<nsISupports>, nsISupports>,
+              "nsISupports works with ScriptableInterfaceType");
+static_assert(
+    std::is_same_v<ScriptableInterfaceType<nsIGlobalObject>, nsISupports>,
+    "non-scriptable interfaces get a fallback");
+static_assert(std::is_same_v<ScriptableInterfaceType<nsIObserver>, nsIObserver>,
+              "scriptable interfaces should get the correct type");
+static_assert(std::is_same_v<ScriptableInterfaceType<nsIRunnable>, nsIRunnable>,
+              "scriptable interfaces should get the correct type");
+class SingleScriptableInterface : public nsIObserver {};
+static_assert(
+    std::is_same_v<ScriptableInterfaceType<SingleScriptableInterface>,
+                   nsIObserver>,
+    "Concrete type with one scriptable interface picks the correct interface");
+class MultiScriptableInterface : public nsIObserver, public nsIRunnable {};
+static_assert(std::is_same_v<ScriptableInterfaceType<MultiScriptableInterface>,
+                             nsISupports>,
+              "Concrete type with multiple scriptable interfaces falls back");
+}  // namespace binding_detail
 }  // namespace dom
 }  // namespace mozilla
diff --git a/dom/bindings/ToJSValue.h b/dom/bindings/ToJSValue.h
index cc4d86ba08..e7bcabbe5e 100644
--- a/dom/bindings/ToJSValue.h
+++ b/dom/bindings/ToJSValue.h
@@ -31,6 +31,10 @@ class WindowProxyHolder;
 MOZ_MUST_USE bool ToJSValue(JSContext* aCx, const nsAString& aArgument,
                             JS::MutableHandle<JS::Value> aValue);
 
+// Treats the input as UTF-8, and throws otherwise.
+MOZ_MUST_USE bool ToJSValue(JSContext* aCx, const nsACString& aArgument,
+                            JS::MutableHandle<JS::Value> aValue);
+
 // Accept booleans.  But be careful here: if we just have a function that takes
 // a boolean argument, then any pointer that doesn't match one of our other
 // signatures/templates will get treated as a boolean, which is clearly not
@@ -189,6 +193,32 @@ MOZ_MUST_USE
   return true;
 }
 
+namespace binding_detail {
+// Helper type alias for picking a script-exposable non-wrappercached XPIDL
+// interface to expose to JS code. Falls back to `nsISupports` if the specific
+// interface type is ambiguous.
+template <typename T, typename = void>
+struct GetScriptableInterfaceType {
+  using Type = nsISupports;
+
+  static_assert(std::is_base_of_v<nsISupports, T>,
+                "T must inherit from nsISupports");
+};
+template <typename T>
+struct GetScriptableInterfaceType<
+    T, std::void_t<typename T::ScriptableInterfaceType>> {
+  using Type = typename T::ScriptableInterfaceType;
+
+  static_assert(std::is_base_of_v<Type, T>,
+                "T must inherit from ScriptableInterfaceType");
+  static_assert(std::is_base_of_v<nsISupports, Type>,
+                "ScriptableInterfaceType must inherit from nsISupports");
+};
+
+template <typename T>
+using ScriptableInterfaceType = typename GetScriptableInterfaceType<T>::Type;
+}  // namespace binding_detail
+
 // Accept objects that inherit from nsISupports but not nsWrapperCache (e.g.
 // DOM File).
 template <class T>
@@ -202,7 +232,9 @@ ToJSValue(JSContext* aCx, T& aArgument, JS::MutableHandle<JS::Value> aValue) {
 
   xpcObjectHelper helper(ToSupports(&aArgument));
   JS::Rooted<JSObject*> scope(aCx, JS::CurrentGlobalOrNull(aCx));
-  return XPCOMObjectToJsval(aCx, scope, helper, nullptr, true, aValue);
+  const nsIID& iid =
+      NS_GET_TEMPLATE_IID(binding_detail::ScriptableInterfaceType<T>);
+  return XPCOMObjectToJsval(aCx, scope, helper, &iid, true, aValue);
 }
 
 MOZ_MUST_USE bool ToJSValue(JSContext* aCx, const WindowProxyHolder& aArgument,
diff --git a/dom/bindings/parser/WebIDL.py b/dom/bindings/parser/WebIDL.py
index 4f6cf049f4..43fca07036 100644
--- a/dom/bindings/parser/WebIDL.py
+++ b/dom/bindings/parser/WebIDL.py
@@ -3473,7 +3473,7 @@ def withExtendedAttributes(self, attrs):
                                       [self.location, attribute.location])
                 assert not self.nullable()
                 if not attribute.hasValue():
-                    raise WebIDLError("[TreatNullAs] must take an identifier argument"
+                    raise WebIDLError("[TreatNullAs] must take an identifier argument",
                                       [attribute.location])
                 value = attribute.value()
                 if value != 'EmptyString':
@@ -5457,7 +5457,7 @@ def handleExtendedAttribute(self, attr):
                                   [attr.location])
             if identifier == "CrossOriginCallable" and self.isStatic():
                 raise WebIDLError("[CrossOriginCallable] is only allowed on non-static "
-                                  "attributes"
+                                  "attributes",
                                   [attr.location, self.location])
         elif identifier == "Pure":
             if not attr.noArguments():
diff --git a/dom/cache/DBSchema.cpp b/dom/cache/DBSchema.cpp
index 666af38804..5eb2a03c7e 100644
--- a/dom/cache/DBSchema.cpp
+++ b/dom/cache/DBSchema.cpp
@@ -20,6 +20,7 @@
 #include "mozIStorageStatement.h"
 #include "mozStorageHelper.h"
 #include "nsCOMPtr.h"
+#include "nsComponentManagerUtils.h"
 #include "nsCRT.h"
 #include "nsHttp.h"
 #include "nsIContentPolicy.h"
@@ -332,7 +333,10 @@ static_assert(nsIContentPolicy::TYPE_INVALID == 0 &&
                   nsIContentPolicy::TYPE_INTERNAL_MODULE == 45 &&
                   nsIContentPolicy::TYPE_INTERNAL_MODULE_PRELOAD == 46 &&
                   nsIContentPolicy::TYPE_INTERNAL_DTD == 47 &&
-                  nsIContentPolicy::TYPE_INTERNAL_FORCE_ALLOWED_DTD == 48,
+                  nsIContentPolicy::TYPE_INTERNAL_FORCE_ALLOWED_DTD == 48 &&
+                  nsIContentPolicy::TYPE_INTERNAL_AUDIOWORKLET == 49 &&
+                  nsIContentPolicy::TYPE_INTERNAL_PAINTWORKLET == 50 &&
+                  nsIContentPolicy::TYPE_INTERNAL_FONT_PRELOAD == 51,
               "nsContentPolicyType values are as expected");
 
 namespace {
diff --git a/dom/chrome-webidl/ChannelWrapper.webidl b/dom/chrome-webidl/ChannelWrapper.webidl
index b541212cb8..367f0a1a65 100644
--- a/dom/chrome-webidl/ChannelWrapper.webidl
+++ b/dom/chrome-webidl/ChannelWrapper.webidl
@@ -73,9 +73,12 @@ interface ChannelWrapper : EventTarget {
 
   /**
    * Cancels the request with the given nsresult status code.
+   *
+   * The optional reason parameter should be one of the BLOCKING_REASON
+   * constants from nsILoadInfo.idl
    */
   [Throws]
-  void cancel(unsigned long result);
+  void cancel(unsigned long result, optional unsigned long reason = 0);
 
   /**
    * Redirects the wrapped HTTP channel to the given URI. For other channel
diff --git a/dom/events/Clipboard.cpp b/dom/events/Clipboard.cpp
index 7346990d4e..5884bcbfa1 100644
--- a/dom/events/Clipboard.cpp
+++ b/dom/events/Clipboard.cpp
@@ -10,9 +10,11 @@
 #include "mozilla/dom/DataTransfer.h"
 #include "mozilla/dom/DataTransferItemList.h"
 #include "mozilla/dom/DataTransferItem.h"
+#include "mozilla/dom/Document.h"
 #include "mozilla/StaticPrefs_dom.h"
 #include "nsIClipboard.h"
 #include "nsComponentManagerUtils.h"
+#include "nsServiceManagerUtils.h"
 #include "nsITransferable.h"
 #include "nsArrayUtils.h"
 
diff --git a/dom/fetch/Fetch.h b/dom/fetch/Fetch.h
index c403a761f9..b391181701 100644
--- a/dom/fetch/Fetch.h
+++ b/dom/fetch/Fetch.h
@@ -5,8 +5,6 @@
 #ifndef mozilla_dom_Fetch_h
 #define mozilla_dom_Fetch_h
 
-#include "nsAutoPtr.h"
-
 #include "nsCOMPtr.h"
 #include "nsError.h"
 #include "nsProxyRelease.h"
diff --git a/dom/fetch/FetchDriver.cpp b/dom/fetch/FetchDriver.cpp
index a96805b10f..08057707cb 100644
--- a/dom/fetch/FetchDriver.cpp
+++ b/dom/fetch/FetchDriver.cpp
@@ -7,6 +7,7 @@
 
 #include "nsIAsyncVerifyRedirectCallback.h"
 #include "mozilla/dom/Document.h"
+#include "nsIFile.h"
 #include "nsIInputStream.h"
 #include "nsIOutputStream.h"
 #include "nsIFileChannel.h"
@@ -258,7 +259,7 @@ AlternativeDataStreamListener::OnDataAvailable(nsIRequest* aRequest,
                                                uint32_t aCount) {
   if (mStatus == AlternativeDataStreamListener::LOADING) {
     MOZ_ASSERT(mPipeAlternativeOutputStream);
-    uint32_t read;
+    uint32_t read = 0;
     return aInputStream->ReadSegments(
         NS_CopySegmentToStream, mPipeAlternativeOutputStream, aCount, &read);
   }
@@ -357,6 +358,84 @@ FetchDriver::~FetchDriver() {
   MOZ_ASSERT(mResponseAvailableCalled);
 }
 
+already_AddRefed<PreloaderBase> FetchDriver::FindPreload(nsIURI* aURI) {
+  // Decide if we allow reuse of an existing <link rel=preload as=fetch>
+  // response for this request.  First examine this fetch requets itself if it
+  // is 'pure' enough to use the response and then try to find a preload.
+
+  if (!mDocument) {
+    // Preloads are mapped on the document, no document, no preload.
+    return nullptr;
+  }
+  CORSMode cors;
+  switch (mRequest->Mode()) {
+    case RequestMode::No_cors:
+      cors = CORSMode::CORS_NONE;
+      break;
+    case RequestMode::Cors:
+      cors = mRequest->GetCredentialsMode() == RequestCredentials::Include
+                 ? CORSMode::CORS_USE_CREDENTIALS
+                 : CORSMode::CORS_ANONYMOUS;
+      break;
+    default:
+      // Can't be satisfied by a preload because preload cannot define any of
+      // remaining modes.
+      return nullptr;
+  }
+  if (!mRequest->Headers()->HasOnlySimpleHeaders()) {
+    // Preload can't set any headers.
+    return nullptr;
+  }
+  if (!mRequest->GetIntegrity().IsEmpty()) {
+    // There is currently no support for SRI checking in the fetch preloader.
+    return nullptr;
+  }
+  if (mRequest->GetCacheMode() != RequestCache::Default) {
+    // Preload can only go with the default caching mode.
+    return nullptr;
+  }
+  if (mRequest->SkipServiceWorker()) {
+    // Preload can't be forbidden interception.
+    return nullptr;
+  }
+  if (mRequest->GetRedirectMode() != RequestRedirect::Follow) {
+    // Preload always follows redirects.
+    return nullptr;
+  }
+  nsAutoCString method;
+  mRequest->GetMethod(method);
+  if (!method.EqualsLiteral("GET")) {
+    // Preload can only do GET, this also eliminates the case we do upload, so
+    // no need to check if the request has any body to send out.
+    return nullptr;
+  }
+
+  // OK, this request can be satisfied by a preloaded response, try to find one.
+
+  // TODO - check if we need to perform step 5 and 6 before using
+  // mRequest->ReferrerPolicy_() here.
+  auto preloadKey =
+      PreloadHashKey::CreateAsFetch(aURI, cors, mRequest->ReferrerPolicy_());
+  return mDocument->Preloads().LookupPreload(&preloadKey);
+}
+
+void FetchDriver::UpdateReferrerInfoFromNewChannel(nsIChannel* aChannel) {
+  nsCOMPtr<nsIHttpChannel> httpChannel = do_QueryInterface(aChannel);
+  if (!httpChannel) {
+    return;
+  }
+
+  nsCOMPtr<nsIReferrerInfo> referrerInfo = httpChannel->GetReferrerInfo();
+  if (!referrerInfo) {
+    return;
+  }
+
+  nsAutoString computedReferrerSpec;
+  mRequest->SetReferrerPolicy(referrerInfo->ReferrerPolicy());
+  Unused << referrerInfo->GetComputedReferrerSpec(computedReferrerSpec);
+  mRequest->SetReferrer(computedReferrerSpec);
+}
+
 nsresult FetchDriver::Fetch(AbortSignalImpl* aSignalImpl,
                             FetchDriverObserver* aObserver) {
   AssertIsOnMainThread();
@@ -457,6 +536,36 @@ nsresult FetchDriver::HttpFetch(
     }
   }
 
+  RefPtr<PreloaderBase> fetchPreload = FindPreload(uri);
+  if (fetchPreload) {
+    fetchPreload->RemoveSelf(mDocument);
+    fetchPreload->NotifyUsage(PreloaderBase::LoadBackground::Keep);
+
+    rv = fetchPreload->AsyncConsume(this);
+    if (NS_SUCCEEDED(rv)) {
+      mFromPreload = true;
+
+      mChannel = fetchPreload->Channel();
+      MOZ_ASSERT(mChannel);
+      mChannel->SetNotificationCallbacks(this);
+
+      // Copied from AsyncOnChannelRedirect.
+      for (const auto& redirect : fetchPreload->Redirects()) {
+        if (redirect.Flags() & nsIChannelEventSink::REDIRECT_INTERNAL) {
+          mRequest->SetURLForInternalRedirect(redirect.Flags(), redirect.Spec(),
+                                              redirect.Fragment());
+        } else {
+          mRequest->AddURL(redirect.Spec(), redirect.Fragment());
+        }
+      }
+
+      return NS_OK;
+    }
+
+    // The preload failed to be consumed.  Behave like there were no preload.
+    fetchPreload = nullptr;
+  }
+
   // Step 2 deals with letting ServiceWorkers intercept requests. This is
   // handled by Necko after the channel is opened.
   // FIXME(nsm): Bug 1119026: The channel's skip service worker flag should be
@@ -584,7 +693,7 @@ nsresult FetchDriver::HttpFetch(
     NS_ENSURE_SUCCESS(rv, rv);
 
     // Set the same headers.
-    SetRequestHeaders(httpChan);
+    SetRequestHeaders(httpChan, false);
 
     // Step 5 of https://fetch.spec.whatwg.org/#main-fetch
     // If request's referrer policy is the empty string and request's client is
@@ -808,6 +917,11 @@ FetchDriver::OnStartRequest(nsIRequest* aRequest) {
   // In that case we will get a simulated OnStartRequest() and then the real
   // channel will call in with an errored OnStartRequest().
 
+  if (mFromPreload && mAborted) {
+    aRequest->Cancel(NS_BINDING_ABORTED);
+    return NS_BINDING_ABORTED;
+  }
+
   if (!mChannel) {
     MOZ_ASSERT(!mObserver);
     return NS_BINDING_ABORTED;
@@ -1075,7 +1189,7 @@ FetchDriver::OnStartRequest(nsIRequest* aRequest) {
     SRICheck::IntegrityMetadata(mRequest->GetIntegrity(), sourceUri, reporter,
                                 &mSRIMetadata);
     mSRIDataVerifier =
-        new SRICheckDataVerifier(mSRIMetadata, sourceUri, reporter);
+        MakeUnique<SRICheckDataVerifier>(mSRIMetadata, sourceUri, reporter);
 
     // Do not retarget off main thread when using SRI API.
     return NS_OK;
@@ -1193,7 +1307,8 @@ FetchDriver::OnDataAvailable(nsIRequest* aRequest, nsIInputStream* aInputStream,
       ShouldCheckSRI(mRequest, mResponse)) {
     MOZ_ASSERT(mSRIDataVerifier);
 
-    SRIVerifierAndOutputHolder holder(mSRIDataVerifier, mPipeOutputStream);
+    SRIVerifierAndOutputHolder holder(mSRIDataVerifier.get(),
+                                      mPipeOutputStream);
     rv = aInputStream->ReadSegments(CopySegmentToStreamAndSRI, &holder, aCount,
                                     &aRead);
   } else {
@@ -1321,9 +1436,18 @@ NS_IMETHODIMP
 FetchDriver::AsyncOnChannelRedirect(nsIChannel* aOldChannel,
                                     nsIChannel* aNewChannel, uint32_t aFlags,
                                     nsIAsyncVerifyRedirectCallback* aCallback) {
-  nsCOMPtr<nsIHttpChannel> httpChannel = do_QueryInterface(aNewChannel);
-  if (httpChannel) {
-    SetRequestHeaders(httpChannel);
+  nsCOMPtr<nsIHttpChannel> oldHttpChannel = do_QueryInterface(aOldChannel);
+  nsCOMPtr<nsIHttpChannel> newHttpChannel = do_QueryInterface(aNewChannel);
+  if (oldHttpChannel && newHttpChannel) {
+    nsAutoCString method;
+    mRequest->GetMethod(method);
+
+    // Fetch 4.4.11
+    bool rewriteToGET = false;
+    Unused << oldHttpChannel->ShouldStripRequestBodyHeader(method,
+                                                           &rewriteToGET);
+
+    SetRequestHeaders(newHttpChannel, rewriteToGET);
   }
 
   // "HTTP-redirect fetch": step 14 "Append locationURL to request's URL list."
@@ -1359,19 +1483,7 @@ FetchDriver::AsyncOnChannelRedirect(nsIChannel* aOldChannel,
 
   // In redirect, httpChannel already took referrer-policy into account, so
   // updates request’s associated referrer policy from channel.
-  if (httpChannel) {
-    nsAutoString computedReferrerSpec;
-    nsCOMPtr<nsIReferrerInfo> referrerInfo = httpChannel->GetReferrerInfo();
-    if (referrerInfo) {
-      mRequest->SetReferrerPolicy(referrerInfo->ReferrerPolicy());
-      Unused << referrerInfo->GetComputedReferrerSpec(computedReferrerSpec);
-    }
-
-    // Step 8 https://fetch.spec.whatwg.org/#main-fetch
-    // If request’s referrer is not "no-referrer" (empty), set request’s
-    // referrer to the result of invoking determine request’s referrer.
-    mRequest->SetReferrer(computedReferrerSpec);
-  }
+  UpdateReferrerInfoFromNewChannel(aNewChannel);
 
   aCallback->OnRedirectVerifyCallback(NS_OK);
   return NS_OK;
@@ -1423,7 +1535,8 @@ void FetchDriver::SetController(
   mController = aController;
 }
 
-void FetchDriver::SetRequestHeaders(nsIHttpChannel* aChannel) const {
+void FetchDriver::SetRequestHeaders(nsIHttpChannel* aChannel,
+                                    bool aStripRequestBodyHeader) const {
   MOZ_ASSERT(aChannel);
 
   // nsIHttpChannel has a set of pre-configured headers (Accept,
@@ -1436,6 +1549,14 @@ void FetchDriver::SetRequestHeaders(nsIHttpChannel* aChannel) const {
   AutoTArray<InternalHeaders::Entry, 5> headers;
   mRequest->Headers()->GetEntries(headers);
   for (uint32_t i = 0; i < headers.Length(); ++i) {
+    if (aStripRequestBodyHeader &&
+        (headers[i].mName.LowerCaseEqualsASCII("content-type") ||
+         headers[i].mName.LowerCaseEqualsASCII("content-encoding") ||
+         headers[i].mName.LowerCaseEqualsASCII("content-language") ||
+         headers[i].mName.LowerCaseEqualsASCII("content-location"))) {
+      continue;
+    }
+
     bool alreadySet = headersSet.Contains(headers[i].mName);
     if (!alreadySet) {
       headersSet.AppendElement(headers[i].mName);
@@ -1480,6 +1601,8 @@ void FetchDriver::Abort() {
     mChannel->Cancel(NS_BINDING_ABORTED);
     mChannel = nullptr;
   }
+
+  mAborted = true;
 }
 
 }  // namespace dom
diff --git a/dom/fetch/FetchDriver.h b/dom/fetch/FetchDriver.h
index f71edb03e8..232d9ea346 100644
--- a/dom/fetch/FetchDriver.h
+++ b/dom/fetch/FetchDriver.h
@@ -14,6 +14,7 @@
 #include "mozilla/dom/SerializedStackHolder.h"
 #include "mozilla/dom/SRIMetadata.h"
 #include "mozilla/RefPtr.h"
+#include "mozilla/UniquePtr.h"
 
 #include "mozilla/DebugOnly.h"
 
@@ -136,7 +137,7 @@ class FetchDriver final : public nsIStreamListener,
   Maybe<ClientInfo> mClientInfo;
   Maybe<ServiceWorkerDescriptor> mController;
   nsCOMPtr<nsIChannel> mChannel;
-  nsAutoPtr<SRICheckDataVerifier> mSRIDataVerifier;
+  UniquePtr<SRICheckDataVerifier> mSRIDataVerifier;
   nsCOMPtr<nsIEventTarget> mMainThreadEventTarget;
 
   nsCOMPtr<nsICookieSettings> mCookieSettings;
@@ -158,6 +159,16 @@ class FetchDriver final : public nsIStreamListener,
   RefPtr<AlternativeDataStreamListener> mAltDataListener;
   bool mOnStopRequestCalled;
 
+  // This flag is true when this fetch has found a matching preload and is being
+  // satisfied by a its response.
+  bool mFromPreload = false;
+  // This flag is set in call to Abort() and spans the possible window this
+  // fetch doesn't have mChannel (to be cancelled) between reuse of the matching
+  // preload, that has already finished and dropped reference to its channel,
+  // and OnStartRequest notification.  It let's us cancel the load when we get
+  // the channel in OnStartRequest.
+  bool mAborted = false;
+
 #ifdef DEBUG
   bool mResponseAvailableCalled;
   bool mFetchCalled;
@@ -170,6 +181,10 @@ class FetchDriver final : public nsIStreamListener,
   FetchDriver& operator=(const FetchDriver&) = delete;
   ~FetchDriver();
 
+  already_AddRefed<PreloaderBase> FindPreload(nsIURI* aURI);
+
+  void UpdateReferrerInfoFromNewChannel(nsIChannel* aChannel);
+
   nsresult HttpFetch(
       const nsACString& aPreferredAlternativeDataType = EmptyCString());
   // Returns the filtered response sent to the observer.
@@ -179,7 +194,8 @@ class FetchDriver final : public nsIStreamListener,
   // response.
   void FailWithNetworkError(nsresult rv);
 
-  void SetRequestHeaders(nsIHttpChannel* aChannel) const;
+  void SetRequestHeaders(nsIHttpChannel* aChannel,
+                         bool aStripRequestBodyHeader) const;
 
   void FinishOnStopRequest(AlternativeDataStreamListener* aAltDataListener);
 };
diff --git a/dom/fetch/FetchUtil.cpp b/dom/fetch/FetchUtil.cpp
index dce0cef2a0..d656385b30 100644
--- a/dom/fetch/FetchUtil.cpp
+++ b/dom/fetch/FetchUtil.cpp
@@ -4,6 +4,7 @@
 
 #include "FetchUtil.h"
 
+#include "nsCRT.h"
 #include "nsError.h"
 #include "nsString.h"
 #include "mozilla/dom/Document.h"
diff --git a/dom/fetch/InternalRequest.cpp b/dom/fetch/InternalRequest.cpp
index 8913ed63f0..2146a286b5 100644
--- a/dom/fetch/InternalRequest.cpp
+++ b/dom/fetch/InternalRequest.cpp
@@ -255,6 +255,7 @@ RequestDestination InternalRequest::MapContentPolicyTypeToRequestDestination(
       destination = RequestDestination::_empty;
       break;
     case nsIContentPolicy::TYPE_FONT:
+    case nsIContentPolicy::TYPE_INTERNAL_FONT_PRELOAD:
       destination = RequestDestination::Font;
       break;
     case nsIContentPolicy::TYPE_MEDIA:
@@ -293,6 +294,12 @@ RequestDestination InternalRequest::MapContentPolicyTypeToRequestDestination(
     case nsIContentPolicy::TYPE_SPECULATIVE:
       destination = RequestDestination::_empty;
       break;
+    case nsIContentPolicy::TYPE_INTERNAL_AUDIOWORKLET:
+      destination = RequestDestination::Audioworklet;
+      break;
+    case nsIContentPolicy::TYPE_INTERNAL_PAINTWORKLET:
+      destination = RequestDestination::Paintworklet;
+      break;
     default:
       MOZ_ASSERT(false, "Unhandled nsContentPolicyType value");
       break;
diff --git a/dom/fetch/InternalRequest.h b/dom/fetch/InternalRequest.h
index 85b428b48f..5429651cb3 100644
--- a/dom/fetch/InternalRequest.h
+++ b/dom/fetch/InternalRequest.h
@@ -34,15 +34,15 @@ namespace dom {
  * RequestDestination| nsContentPolicyType
  * ------------------+--------------------
  * audio             | TYPE_INTERNAL_AUDIO
- * audioworklet      | TODO
+ * audioworklet      | TYPE_INTERNAL_AUDIOWORKLET
  * document          | TYPE_DOCUMENT, TYPE_INTERNAL_IFRAME, TYPE_SUBDOCUMENT
  * embed             | TYPE_INTERNAL_EMBED
- * font              | TYPE_FONT
+ * font              | TYPE_FONT, TYPE_INTERNAL_FONT_PRELOAD
  * image             | TYPE_INTERNAL_IMAGE, TYPE_INTERNAL_IMAGE_PRELOAD,
  *                   | TYPE_IMAGE, TYPE_INTERNAL_IMAGE_FAVICON, TYPE_IMAGESET
  * manifest          | TYPE_WEB_MANIFEST
  * object            | TYPE_INTERNAL_OBJECT, TYPE_OBJECT
- * "paintworklet"    | TODO
+ * "paintworklet"    | TYPE_INTERNAL_PAINTWORKLET
  * report"           | TODO
  * script            | TYPE_INTERNAL_SCRIPT, TYPE_INTERNAL_SCRIPT_PRELOAD,
  *                   | TYPE_INTERNAL_MODULE, TYPE_INTERNAL_MODULE_PRELOAD,
diff --git a/dom/fetch/Request.cpp b/dom/fetch/Request.cpp
index 61857b8291..5e77d27926 100644
--- a/dom/fetch/Request.cpp
+++ b/dom/fetch/Request.cpp
@@ -181,7 +181,7 @@ void GetRequestURLFromChrome(const nsAString& aInput, nsAString& aRequestURL,
     return;
   }
 }
-already_AddRefed<URL> ParseURLFromWorker(const GlobalObject& aGlobal,
+already_AddRefed<URL> ParseURLFromWorker(nsIGlobalObject* aGlobal,
                                          const nsAString& aInput,
                                          ErrorResult& aRv) {
   WorkerPrivate* worker = GetCurrentThreadWorkerPrivate();
@@ -189,16 +189,15 @@ already_AddRefed<URL> ParseURLFromWorker(const GlobalObject& aGlobal,
   worker->AssertIsOnWorkerThread();
 
   NS_ConvertUTF8toUTF16 baseURL(worker->GetLocationInfo().mHref);
-  RefPtr<URL> url =
-      URL::Constructor(aGlobal.GetAsSupports(), aInput, baseURL, aRv);
+  RefPtr<URL> url = URL::Constructor(aGlobal, aInput, baseURL, aRv);
   if (NS_WARN_IF(aRv.Failed())) {
     aRv.ThrowTypeError<MSG_INVALID_URL>(NS_ConvertUTF16toUTF8(aInput));
   }
   return url.forget();
 }
-void GetRequestURLFromWorker(const GlobalObject& aGlobal,
-                             const nsAString& aInput, nsAString& aRequestURL,
-                             nsACString& aURLfragment, ErrorResult& aRv) {
+void GetRequestURLFromWorker(nsIGlobalObject* aGlobal, const nsAString& aInput,
+                             nsAString& aRequestURL, nsACString& aURLfragment,
+                             ErrorResult& aRv) {
   RefPtr<URL> url = ParseURLFromWorker(aGlobal, aInput, aRv);
   if (aRv.Failed()) {
     return;
@@ -264,11 +263,19 @@ already_AddRefed<Request> Request::Constructor(const GlobalObject& aGlobal,
                                                const RequestOrUSVString& aInput,
                                                const RequestInit& aInit,
                                                ErrorResult& aRv) {
+  nsCOMPtr<nsIGlobalObject> global = do_QueryInterface(aGlobal.GetAsSupports());
+  return Constructor(global, aGlobal.Context(), aInput, aInit, aRv);
+}
+
+/*static*/
+already_AddRefed<Request> Request::Constructor(nsIGlobalObject* aGlobal,
+                                               JSContext* aCx,
+                                               const RequestOrUSVString& aInput,
+                                               const RequestInit& aInit,
+                                               ErrorResult& aRv) {
   bool hasCopiedBody = false;
   RefPtr<InternalRequest> request;
 
-  nsCOMPtr<nsIGlobalObject> global = do_QueryInterface(aGlobal.GetAsSupports());
-
   RefPtr<AbortSignal> signal;
 
   if (aInput.IsRequest()) {
@@ -299,7 +306,7 @@ already_AddRefed<Request> Request::Constructor(const GlobalObject& aGlobal,
     nsAutoString requestURL;
     nsCString fragment;
     if (NS_IsMainThread()) {
-      nsCOMPtr<nsPIDOMWindowInner> inner(do_QueryInterface(global));
+      nsCOMPtr<nsPIDOMWindowInner> inner(do_QueryInterface(aGlobal));
       Document* doc = inner ? inner->GetExtantDoc() : nullptr;
       if (doc) {
         GetRequestURLFromDocument(doc, input, requestURL, fragment, aRv);
@@ -315,7 +322,7 @@ already_AddRefed<Request> Request::Constructor(const GlobalObject& aGlobal,
     }
     request = new InternalRequest(NS_ConvertUTF16toUTF8(requestURL), fragment);
   }
-  request = request->GetRequestConstructorCopy(global, aRv);
+  request = request->GetRequestConstructorCopy(aGlobal, aRv);
   if (NS_WARN_IF(aRv.Failed())) {
     return nullptr;
   }
@@ -353,7 +360,7 @@ already_AddRefed<Request> Request::Constructor(const GlobalObject& aGlobal,
     } else {
       nsAutoString referrerURL;
       if (NS_IsMainThread()) {
-        nsCOMPtr<nsPIDOMWindowInner> inner(do_QueryInterface(global));
+        nsCOMPtr<nsPIDOMWindowInner> inner(do_QueryInterface(aGlobal));
         Document* doc = inner ? inner->GetExtantDoc() : nullptr;
         nsCOMPtr<nsIURI> uri;
         if (doc) {
@@ -372,7 +379,7 @@ already_AddRefed<Request> Request::Constructor(const GlobalObject& aGlobal,
         uri->GetSpec(spec);
         CopyUTF8toUTF16(spec, referrerURL);
         if (!referrerURL.EqualsLiteral(kFETCH_CLIENT_REFERRER_STR)) {
-          nsCOMPtr<nsIPrincipal> principal = global->PrincipalOrNull();
+          nsCOMPtr<nsIPrincipal> principal = aGlobal->PrincipalOrNull();
           if (principal) {
             nsresult rv =
                 principal->CheckMayLoad(uri, /* report */ false,
@@ -422,7 +429,7 @@ already_AddRefed<Request> Request::Constructor(const GlobalObject& aGlobal,
   UniquePtr<mozilla::ipc::PrincipalInfo> principalInfo;
 
   if (NS_IsMainThread()) {
-    nsCOMPtr<nsPIDOMWindowInner> window = do_QueryInterface(global);
+    nsCOMPtr<nsPIDOMWindowInner> window = do_QueryInterface(aGlobal);
     if (window) {
       nsCOMPtr<Document> doc;
       doc = window->GetExtantDoc();
@@ -504,8 +511,7 @@ already_AddRefed<Request> Request::Constructor(const GlobalObject& aGlobal,
 
   RefPtr<InternalHeaders> headers;
   if (aInit.mHeaders.WasPassed()) {
-    RefPtr<Headers> h =
-        Headers::Constructor(aGlobal, aInit.mHeaders.Value(), aRv);
+    RefPtr<Headers> h = Headers::Create(aGlobal, aInit.mHeaders.Value(), aRv);
     if (aRv.Failed()) {
       return nullptr;
     }
@@ -585,7 +591,7 @@ already_AddRefed<Request> Request::Constructor(const GlobalObject& aGlobal,
     }
   }
 
-  RefPtr<Request> domRequest = new Request(global, request, signal);
+  RefPtr<Request> domRequest = new Request(aGlobal, request, signal);
   domRequest->SetMimeType();
 
   if (aInput.IsRequest()) {
@@ -594,7 +600,7 @@ already_AddRefed<Request> Request::Constructor(const GlobalObject& aGlobal,
     inputReq->GetBody(getter_AddRefs(body));
     if (body) {
       inputReq->SetBody(nullptr, 0);
-      inputReq->SetBodyUsed(aGlobal.Context(), aRv);
+      inputReq->SetBodyUsed(aCx, aRv);
       if (NS_WARN_IF(aRv.Failed())) {
         return nullptr;
       }
diff --git a/dom/fetch/Request.h b/dom/fetch/Request.h
index a2e5400c7d..e2381d9840 100644
--- a/dom/fetch/Request.h
+++ b/dom/fetch/Request.h
@@ -102,6 +102,12 @@ class Request final : public FetchBody<Request>, public nsWrapperCache {
                                                const RequestInit& aInit,
                                                ErrorResult& rv);
 
+  static already_AddRefed<Request> Constructor(nsIGlobalObject* aGlobal,
+                                               JSContext* aCx,
+                                               const RequestOrUSVString& aInput,
+                                               const RequestInit& aInit,
+                                               ErrorResult& rv);
+
   nsIGlobalObject* GetParentObject() const { return mOwner; }
 
   already_AddRefed<Request> Clone(ErrorResult& aRv);
diff --git a/dom/fetch/tests/crashtests/1664514.html b/dom/fetch/tests/crashtests/1664514.html
new file mode 100644
index 0000000000..dae325d2a7
--- /dev/null
+++ b/dom/fetch/tests/crashtests/1664514.html
@@ -0,0 +1,6 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<h3>Set <code>privacy.file_unique_origin</code> to false when testing this.</h3>
+<script>
+  fetch("./url.url")
+</script>
diff --git a/dom/fetch/tests/crashtests/crashtests.list b/dom/fetch/tests/crashtests/crashtests.list
index a56dfb39e8..b3210cd4d8 100644
--- a/dom/fetch/tests/crashtests/crashtests.list
+++ b/dom/fetch/tests/crashtests/crashtests.list
@@ -1 +1,2 @@
-load 1577196.html
\ No newline at end of file
+load 1577196.html
+pref(privacy.file_unique_origin,false) load 1664514.html
diff --git a/dom/fetch/tests/crashtests/url.url b/dom/fetch/tests/crashtests/url.url
new file mode 100644
index 0000000000..500d9ea837
--- /dev/null
+++ b/dom/fetch/tests/crashtests/url.url
@@ -0,0 +1,5 @@
+[{000214A0-0000-0000-C000-000000000046}]
+Prop3=19,11
+[InternetShortcut]
+IDList=
+URL=http://localhost:8000/
diff --git a/dom/file/ipc/FileCreatorParent.cpp b/dom/file/ipc/FileCreatorParent.cpp
index b65fa01b2a..640d0f6d45 100644
--- a/dom/file/ipc/FileCreatorParent.cpp
+++ b/dom/file/ipc/FileCreatorParent.cpp
@@ -6,9 +6,9 @@
 #include "mozilla/dom/FileBlobImpl.h"
 #include "mozilla/dom/IPCBlobUtils.h"
 #include "mozilla/dom/MultipartBlobImpl.h"
+#include "nsIFile.h"
 
-namespace mozilla {
-namespace dom {
+namespace mozilla::dom {
 
 FileCreatorParent::FileCreatorParent()
     : mBackgroundEventTarget(GetCurrentThreadEventTarget()), mIPCActive(true) {}
@@ -132,5 +132,4 @@ nsresult FileCreatorParent::CreateBlobImpl(
   return NS_OK;
 }
 
-}  // namespace dom
-}  // namespace mozilla
+}  // namespace mozilla::dom
diff --git a/dom/file/uri/BlobURLProtocolHandler.cpp b/dom/file/uri/BlobURLProtocolHandler.cpp
index 5acf703c7a..3b41e93332 100644
--- a/dom/file/uri/BlobURLProtocolHandler.cpp
+++ b/dom/file/uri/BlobURLProtocolHandler.cpp
@@ -684,9 +684,9 @@ nsresult BlobURLProtocolHandler::GenerateURIString(nsIPrincipal* aPrincipal,
 
   if (aPrincipal) {
     nsAutoCString origin;
-    rv = nsContentUtils::GetASCIIOrigin(aPrincipal, origin);
-    if (NS_WARN_IF(NS_FAILED(rv))) {
-      return rv;
+    rv = aPrincipal->GetAsciiOrigin(origin);
+    if (NS_FAILED(rv)) {
+      origin.AssignLiteral("null");
     }
 
     aUri.Append(origin);
@@ -826,8 +826,8 @@ BlobURLProtocolHandler::NewChannel(nsIURI* aURI, nsILoadInfo* aLoadInfo,
   // principal and which is never mutated to have a non-zero mPrivateBrowsingId
   // or container.
   if (aLoadInfo &&
-      (!aLoadInfo->LoadingPrincipal() ||
-       !aLoadInfo->LoadingPrincipal()->IsSystemPrincipal()) &&
+      (!aLoadInfo->GetLoadingPrincipal() ||
+       !aLoadInfo->GetLoadingPrincipal()->IsSystemPrincipal()) &&
       !ChromeUtils::IsOriginAttributesEqualIgnoringFPD(
           aLoadInfo->GetOriginAttributes(),
           BasePrincipal::Cast(info->mPrincipal)->OriginAttributesRef())) {
diff --git a/dom/filehandle/ActorsParent.cpp b/dom/filehandle/ActorsParent.cpp
index 74eef3ca53..879b59c359 100644
--- a/dom/filehandle/ActorsParent.cpp
+++ b/dom/filehandle/ActorsParent.cpp
@@ -8,6 +8,7 @@
 #include "mozilla/Atomics.h"
 #include "mozilla/Attributes.h"
 #include "mozilla/Unused.h"
+#include "mozilla/dom/BlobImpl.h"
 #include "mozilla/dom/File.h"
 #include "mozilla/dom/PBackgroundFileHandleParent.h"
 #include "mozilla/dom/PBackgroundFileRequestParent.h"
@@ -15,11 +16,11 @@
 #include "mozilla/dom/indexedDB/PBackgroundIDBDatabaseParent.h"
 #include "mozilla/dom/IPCBlobUtils.h"
 #include "mozilla/dom/quota/MemoryOutputStream.h"
-#include "nsAutoPtr.h"
 #include "nsComponentManagerUtils.h"
 #include "nsDebug.h"
 #include "nsError.h"
 #include "nsIEventTarget.h"
+#include "nsIFile.h"
 #include "nsIFileStreams.h"
 #include "nsIInputStream.h"
 #include "nsIOutputStream.h"
@@ -140,7 +141,7 @@ class FileHandleThreadPool::DirectoryInfo {
 };
 
 struct FileHandleThreadPool::StoragesCompleteCallback final {
-  friend class nsAutoPtr<StoragesCompleteCallback>;
+  friend class DefaultDelete<StoragesCompleteCallback>;
 
   nsTArray<nsCString> mDirectoryIds;
   nsCOMPtr<nsIRunnable> mCallback;
@@ -656,11 +657,8 @@ void FileHandleThreadPool::Enqueue(FileHandle* aFileHandle,
 
   DirectoryInfo* directoryInfo;
   if (!mDirectoryInfos.Get(directoryId, &directoryInfo)) {
-    nsAutoPtr<DirectoryInfo> newDirectoryInfo(new DirectoryInfo(this));
-
-    mDirectoryInfos.Put(directoryId, newDirectoryInfo);
-
-    directoryInfo = newDirectoryInfo.forget();
+    directoryInfo = new DirectoryInfo(this);
+    mDirectoryInfos.Put(directoryId, directoryInfo);
   }
 
   FileHandleQueue* existingFileHandleQueue =
@@ -709,11 +707,11 @@ void FileHandleThreadPool::WaitForDirectoriesToComplete(
   MOZ_ASSERT(!aDirectoryIds.IsEmpty());
   MOZ_ASSERT(aCallback);
 
-  nsAutoPtr<StoragesCompleteCallback> callback(
-      new StoragesCompleteCallback(std::move(aDirectoryIds), aCallback));
+  auto callback =
+      MakeUnique<StoragesCompleteCallback>(std::move(aDirectoryIds), aCallback);
 
-  if (!MaybeFireCallback(callback)) {
-    mCompleteCallbacks.AppendElement(callback.forget());
+  if (!MaybeFireCallback(callback.get())) {
+    mCompleteCallbacks.AppendElement(std::move(callback));
   }
 }
 
@@ -783,8 +781,8 @@ void FileHandleThreadPool::Cleanup() {
     // Run all callbacks manually now.
     for (uint32_t count = mCompleteCallbacks.Length(), index = 0; index < count;
          index++) {
-      nsAutoPtr<StoragesCompleteCallback> completeCallback(
-          mCompleteCallbacks[index].forget());
+      UniquePtr<StoragesCompleteCallback> completeCallback =
+          std::move(mCompleteCallbacks[index]);
       MOZ_ASSERT(completeCallback);
       MOZ_ASSERT(completeCallback->mCallback);
 
@@ -824,7 +822,7 @@ void FileHandleThreadPool::FinishFileHandle(FileHandle* aFileHandle) {
     // See if we need to fire any complete callbacks.
     uint32_t index = 0;
     while (index < mCompleteCallbacks.Length()) {
-      if (MaybeFireCallback(mCompleteCallbacks[index])) {
+      if (MaybeFireCallback(mCompleteCallbacks[index].get())) {
         mCompleteCallbacks.RemoveElementAt(index);
       } else {
         index++;
diff --git a/dom/filehandle/ActorsParent.h b/dom/filehandle/ActorsParent.h
index 69fa366a91..cc6e1084dc 100644
--- a/dom/filehandle/ActorsParent.h
+++ b/dom/filehandle/ActorsParent.h
@@ -8,7 +8,7 @@
 #include "mozilla/dom/FileHandleStorage.h"
 #include "mozilla/dom/PBackgroundMutableFileParent.h"
 #include "mozilla/ipc/BackgroundParent.h"
-#include "nsAutoPtr.h"
+#include "mozilla/UniquePtr.h"
 #include "nsClassHashtable.h"
 #include "nsCOMPtr.h"
 #include "nsHashKeys.h"
@@ -47,7 +47,7 @@ class FileHandleThreadPool final {
 
   nsClassHashtable<nsCStringHashKey, DirectoryInfo> mDirectoryInfos;
 
-  nsTArray<nsAutoPtr<StoragesCompleteCallback>> mCompleteCallbacks;
+  nsTArray<UniquePtr<StoragesCompleteCallback>> mCompleteCallbacks;
 
   bool mShutdownRequested;
   bool mShutdownComplete;
diff --git a/dom/filesystem/Directory.cpp b/dom/filesystem/Directory.cpp
index a8b03f5477..64f234cbb1 100644
--- a/dom/filesystem/Directory.cpp
+++ b/dom/filesystem/Directory.cpp
@@ -8,15 +8,16 @@
 #include "GetFilesTask.h"
 
 #include "nsCharSeparatedTokenizer.h"
+#include "nsIFile.h"
 #include "nsString.h"
+#include "mozilla/dom/BlobImpl.h"
 #include "mozilla/dom/DirectoryBinding.h"
 #include "mozilla/dom/FileSystemBase.h"
 #include "mozilla/dom/FileSystemUtils.h"
 #include "mozilla/dom/OSFileSystem.h"
 #include "mozilla/dom/WorkerPrivate.h"
 
-namespace mozilla {
-namespace dom {
+namespace mozilla::dom {
 
 NS_IMPL_CYCLE_COLLECTION_CLASS(Directory)
 
@@ -195,5 +196,4 @@ FileSystemBase* Directory::GetFileSystem(ErrorResult& aRv) {
   return mFileSystem;
 }
 
-}  // namespace dom
-}  // namespace mozilla
+}  // namespace mozilla::dom
diff --git a/dom/filesystem/FileSystemBase.cpp b/dom/filesystem/FileSystemBase.cpp
index 1e73a549de..d7b032f763 100644
--- a/dom/filesystem/FileSystemBase.cpp
+++ b/dom/filesystem/FileSystemBase.cpp
@@ -4,11 +4,13 @@
 
 #include "mozilla/dom/FileSystemBase.h"
 
+#include "mozilla/ErrorResult.h"
+#include "mozilla/dom/BlobImpl.h"
 #include "nsCharSeparatedTokenizer.h"
+#include "nsIFile.h"
 #include "OSFileSystem.h"
 
-namespace mozilla {
-namespace dom {
+namespace mozilla::dom {
 
 FileSystemBase::FileSystemBase() : mShutdown(false) {}
 
@@ -136,5 +138,4 @@ void FileSystemBase::AssertIsOnOwningThread() const {
   NS_ASSERT_OWNINGTHREAD(FileSystemBase);
 }
 
-}  // namespace dom
-}  // namespace mozilla
+}  // namespace mozilla::dom
diff --git a/dom/flex/Flex.h b/dom/flex/Flex.h
index 964f93c62e..8f3d7778f0 100644
--- a/dom/flex/Flex.h
+++ b/dom/flex/Flex.h
@@ -5,7 +5,6 @@
 #ifndef mozilla_dom_Flex_h
 #define mozilla_dom_Flex_h
 
-#include "mozilla/dom/Element.h"
 #include "mozilla/dom/FlexBinding.h"
 #include "nsISupports.h"
 #include "nsWrapperCache.h"
@@ -15,6 +14,7 @@ class nsFlexContainerFrame;
 namespace mozilla {
 namespace dom {
 
+class Element;
 class FlexLineValues;
 
 class Flex : public nsISupports, public nsWrapperCache {
diff --git a/dom/html/HTMLDialogElement.cpp b/dom/html/HTMLDialogElement.cpp
index 49747a4f6a..f552d0da51 100644
--- a/dom/html/HTMLDialogElement.cpp
+++ b/dom/html/HTMLDialogElement.cpp
@@ -3,10 +3,13 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "mozilla/dom/HTMLDialogElement.h"
+#include "mozilla/dom/ElementBinding.h"
 #include "mozilla/dom/HTMLDialogElementBinding.h"
 #include "mozilla/dom/HTMLUnknownElement.h"
 #include "mozilla/StaticPrefs_dom.h"
 
+#include "nsContentUtils.h"
+
 // Expand NS_IMPL_NS_NEW_HTML_ELEMENT(Dialog) with pref check
 nsGenericHTMLElement* NS_NewHTMLDialogElement(
     already_AddRefed<mozilla::dom::NodeInfo>&& aNodeInfo,
@@ -56,6 +59,7 @@ void HTMLDialogElement::Show() {
   }
   ErrorResult ignored;
   SetOpen(true, ignored);
+  FocusDialog();
   ignored.SuppressException();
 }
 
@@ -90,9 +94,105 @@ void HTMLDialogElement::ShowModal(ErrorResult& aError) {
   }
 
   SetOpen(true, aError);
+  FocusDialog();
+
   aError.SuppressException();
 }
 
+void HTMLDialogElement::FocusDialog() {
+  // 1) If subject is inert, return.
+  // 2) Let control be the first descendant element of subject, in tree
+  // order, that is not inert and has the autofocus attribute specified.
+  if (RefPtr<Document> doc = GetComposedDoc()) {
+    doc->FlushPendingNotifications(FlushType::Frames);
+  }
+
+  Element* control = nullptr;
+  nsIContent* child = GetFirstChild();
+  while (child) {
+    if (child->IsElement()) {
+      nsIFrame* frame = child->GetPrimaryFrame();
+      if (frame && frame->IsFocusable()) {
+        if (child->AsElement()->HasAttr(kNameSpaceID_None,
+                                        nsGkAtoms::autofocus)) {
+          // Find the first descendant of element of subject that this
+          // not inert and has autofucus attribute
+          // inert bug: https://bugzilla.mozilla.org/show_bug.cgi?id=921504
+          control = child->AsElement();
+          break;
+        }
+        // If there isn't one, then let control be the first non-inert
+        // descendant element of subject, in tree order.
+        if (!control) {
+          control = child->AsElement();
+        }
+      }
+    }
+    child = child->GetNextNode(this);
+  }
+  // If there isn't one of those either, then let control be subject.
+  if (!control) {
+    control = this;
+  }
+
+  // 3) Run the focusing steps for control.
+  ErrorResult rv;
+  nsIFrame* frame = control->GetPrimaryFrame();
+  if (frame && frame->IsFocusable()) {
+    control->Focus(FocusOptions(), rv);
+    if (rv.Failed()) {
+      return;
+    }
+  } else {
+    nsIFocusManager* fm = nsFocusManager::GetFocusManager();
+    if (fm) {
+      // Clear the focus which ends up making the body gets focused
+      fm->ClearFocus(OwnerDoc()->GetWindow());
+    }
+  }
+
+  // 4) Let topDocument be the active document of control's node document's
+  // browsing context's top-level browsing context.
+  // 5) If control's node document's origin is not the same as the origin of
+  // topDocument, then return.
+  BrowsingContext* bc = control->OwnerDoc()->GetBrowsingContext();
+  if (bc) {
+    nsCOMPtr<nsIDocShell> docShell = bc->Top()->GetDocShell();
+    if (docShell) {
+      if (Document* topDocument = docShell->GetDocument()) {
+        // 6) Empty topDocument's autofocus candidates.
+        // 7) Set topDocument's autofocus processed flag to true.
+        topDocument->SetAutoFocusFired();
+      }
+    }
+  }
+}
+
+void HTMLDialogElement::QueueCancelDialog() {
+  // queues an element task on the user interaction task source
+  OwnerDoc()
+      ->EventTargetFor(TaskCategory::UI)
+      ->Dispatch(NewRunnableMethod("HTMLDialogElement::RunCancelDialogSteps",
+                                   this,
+                                   &HTMLDialogElement::RunCancelDialogSteps));
+}
+
+void HTMLDialogElement::RunCancelDialogSteps() {
+  // 1) Let close be the result of firing an event named cancel at dialog, with
+  // the cancelable attribute initialized to true.
+  bool defaultAction = true;
+  nsContentUtils::DispatchTrustedEvent(
+      OwnerDoc(), this, NS_LITERAL_STRING("cancel"), CanBubble::eNo,
+      Cancelable::eYes, &defaultAction);
+
+  // 2) If close is true and dialog has an open attribute, then close the dialog
+  // with no return value.
+  if (defaultAction) {
+    Optional<nsAString> retValue;
+    Close(retValue);
+  }
+}
+
 JSObject* HTMLDialogElement::WrapNode(JSContext* aCx,
                                       JS::Handle<JSObject*> aGivenProto) {
   return HTMLDialogElement_Binding::Wrap(aCx, this, aGivenProto);
diff --git a/dom/html/HTMLDialogElement.h b/dom/html/HTMLDialogElement.h
index f29532f869..d2fde899a4 100644
--- a/dom/html/HTMLDialogElement.h
+++ b/dom/html/HTMLDialogElement.h
@@ -42,11 +42,14 @@ class HTMLDialogElement final : public nsGenericHTMLElement {
   void ShowModal(ErrorResult& aError);
 
   bool IsInTopLayer() const;
+  void QueueCancelDialog();
+  void RunCancelDialogSteps();
 
   nsString mReturnValue;
 
  protected:
   virtual ~HTMLDialogElement();
+  void FocusDialog();
   JSObject* WrapNode(JSContext* aCx,
                      JS::Handle<JSObject*> aGivenProto) override;
 
diff --git a/dom/html/HTMLFormElement.cpp b/dom/html/HTMLFormElement.cpp
index 31c469ec41..9680312e5b 100644
--- a/dom/html/HTMLFormElement.cpp
+++ b/dom/html/HTMLFormElement.cpp
@@ -12,7 +12,8 @@
 #include "mozilla/ContentEvents.h"
 #include "mozilla/EventDispatcher.h"
 #include "mozilla/EventStates.h"
-#include "mozilla/UniquePtr.h"
+#include "mozilla/PresShell.h"
+#include "mozilla/UniquePtrExtensions.h"
 #include "mozilla/dom/BindContext.h"
 #include "mozilla/dom/CustomEvent.h"
 #include "mozilla/dom/Document.h"
diff --git a/dom/html/HTMLFormSubmission.cpp b/dom/html/HTMLFormSubmission.cpp
index 0cee85a1dd..11522fc53c 100644
--- a/dom/html/HTMLFormSubmission.cpp
+++ b/dom/html/HTMLFormSubmission.cpp
@@ -8,6 +8,7 @@
 #include "nsCOMPtr.h"
 #include "nsIForm.h"
 #include "mozilla/dom/Document.h"
+#include "nsComponentManagerUtils.h"
 #include "nsGkAtoms.h"
 #include "nsIFormControl.h"
 #include "nsError.h"
diff --git a/dom/html/HTMLImageElement.cpp b/dom/html/HTMLImageElement.cpp
index 3d76a87790..c31a3cab56 100644
--- a/dom/html/HTMLImageElement.cpp
+++ b/dom/html/HTMLImageElement.cpp
@@ -189,6 +189,16 @@ void HTMLImageElement::GetDecoding(nsAString& aValue) {
   GetEnumAttr(nsGkAtoms::decoding, kDecodingTableDefault->tag, aValue);
 }
 
+// https://whatpr.org/html/3752/urls-and-fetching.html#lazy-loading-attributes
+static const nsAttrValue::EnumTable kLoadingTable[] = {
+    {"eager", HTMLImageElement::Loading::Eager},
+    {"lazy", HTMLImageElement::Loading::Lazy},
+    {nullptr, 0}};
+
+void HTMLImageElement::GetLoading(nsAString& aValue) const {
+  GetEnumAttr(nsGkAtoms::loading, kLoadingTable[0].tag, aValue);
+}
+
 already_AddRefed<Promise> HTMLImageElement::Decode(ErrorResult& aRv) {
   return nsImageLoadingContent::QueueDecodeAsync(aRv);
 }
@@ -206,9 +216,15 @@ bool HTMLImageElement::ParseAttribute(int32_t aNamespaceID, nsAtom* aAttribute,
       return true;
     }
     if (aAttribute == nsGkAtoms::decoding) {
-      return aResult.ParseEnumValue(aValue, kDecodingTable, false,
+      return aResult.ParseEnumValue(aValue, kDecodingTable,
+                                    /* aCaseSensitive = */ false,
                                     kDecodingTableDefault);
     }
+    if (aAttribute == nsGkAtoms::loading) {
+      return aResult.ParseEnumValue(aValue, kLoadingTable,
+                                    /* aCaseSensitive = */ false,
+                                    kLoadingTable);
+    }
     if (ParseImageAttribute(aAttribute, aValue, aResult)) {
       return true;
     }
diff --git a/dom/html/HTMLImageElement.h b/dom/html/HTMLImageElement.h
index 7bd67e68e6..2bc2d24e58 100644
--- a/dom/html/HTMLImageElement.h
+++ b/dom/html/HTMLImageElement.h
@@ -181,6 +181,16 @@ class HTMLImageElement final : public nsGenericHTMLElement,
   }
   void GetDecoding(nsAString& aValue);
 
+  enum class Loading : uint8_t {
+    Eager,
+    Lazy,
+  };
+
+  void SetLoading(const nsAString& aLoading, ErrorResult& aError) {
+    SetHTMLAttr(nsGkAtoms::loading, aLoading, aError);
+  }
+  void GetLoading(nsAString&) const;
+
   already_AddRefed<Promise> Decode(ErrorResult& aRv);
 
   ReferrerPolicy GetImageReferrerPolicy() override {
diff --git a/dom/html/HTMLInputElement.cpp b/dom/html/HTMLInputElement.cpp
index d202546934..a953415654 100644
--- a/dom/html/HTMLInputElement.cpp
+++ b/dom/html/HTMLInputElement.cpp
@@ -10,6 +10,7 @@
 #include "mozilla/DebugOnly.h"
 #include "mozilla/dom/Directory.h"
 #include "mozilla/dom/DocumentOrShadowRoot.h"
+#include "mozilla/dom/ElementBinding.h"
 #include "mozilla/dom/FileSystemUtils.h"
 #include "mozilla/dom/GetFilesHelper.h"
 #include "mozilla/dom/HTMLFormSubmission.h"
diff --git a/dom/html/HTMLLegendElement.cpp b/dom/html/HTMLLegendElement.cpp
index 9ae7f1a2bf..43f82614af 100644
--- a/dom/html/HTMLLegendElement.cpp
+++ b/dom/html/HTMLLegendElement.cpp
@@ -3,6 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "mozilla/dom/HTMLLegendElement.h"
+#include "mozilla/dom/ElementBinding.h"
 #include "mozilla/dom/HTMLLegendElementBinding.h"
 #include "nsFocusManager.h"
 #include "nsIFrame.h"
diff --git a/dom/html/HTMLLinkElement.cpp b/dom/html/HTMLLinkElement.cpp
index 7a1b6b2f21..001c2b4302 100644
--- a/dom/html/HTMLLinkElement.cpp
+++ b/dom/html/HTMLLinkElement.cpp
@@ -11,6 +11,7 @@
 #include "mozilla/EventStates.h"
 #include "mozilla/MemoryReporting.h"
 #include "mozilla/Preferences.h"
+#include "mozilla/StaticPrefs_network.h"
 #include "mozilla/dom/BindContext.h"
 #include "mozilla/dom/DocumentInlines.h"
 #include "mozilla/dom/HTMLLinkElementBinding.h"
@@ -23,11 +24,9 @@
 #include "mozilla/dom/Document.h"
 #include "nsINode.h"
 #include "nsIPrefetchService.h"
-#include "nsIStyleSheetLinkingElement.h"
 #include "nsPIDOMWindow.h"
 #include "nsReadableUtils.h"
 #include "nsStyleConsts.h"
-#include "nsStyleLinkElement.h"
 #include "nsUnicharUtils.h"
 #include "nsWindowSizes.h"
 #include "nsIContentPolicy.h"
@@ -70,21 +69,20 @@ NS_IMPL_CYCLE_COLLECTION_CLASS(HTMLLinkElement)
 
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(HTMLLinkElement,
                                                   nsGenericHTMLElement)
-  tmp->nsStyleLinkElement::Traverse(cb);
+  tmp->LinkStyle::Traverse(cb);
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mRelList)
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mSizes)
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
 
 NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(HTMLLinkElement,
                                                 nsGenericHTMLElement)
-  tmp->nsStyleLinkElement::Unlink();
+  tmp->LinkStyle::Unlink();
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mRelList)
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mSizes)
 NS_IMPL_CYCLE_COLLECTION_UNLINK_END
 
 NS_IMPL_ISUPPORTS_CYCLE_COLLECTION_INHERITED(HTMLLinkElement,
-                                             nsGenericHTMLElement,
-                                             nsIStyleSheetLinkingElement, Link)
+                                             nsGenericHTMLElement, Link)
 
 NS_IMPL_ELEMENT_CLONE(HTMLLinkElement)
 
@@ -397,16 +395,31 @@ void HTMLLinkElement::GetLinkTarget(nsAString& aTarget) {
 }
 
 static const DOMTokenListSupportedToken sSupportedRelValues[] = {
-    // Keep this in sync with ToLinkMask in nsStyleLinkElement.cpp.
+    // Keep this and the one below in sync with ToLinkMask in
+    // LinkStyle.cpp.
     // "preload" must come first because it can be disabled.
     "preload",   "prefetch",   "dns-prefetch", "stylesheet", "next",
     "alternate", "preconnect", "icon",         "search",     nullptr};
 
+static const DOMTokenListSupportedToken sSupportedRelValuesWithManifest[] = {
+    // Keep this in sync with ToLinkMask in LinkStyle.cpp.
+    // "preload" and "manifest" must come first because they can be disabled.
+    "preload",   "manifest",   "prefetch", "dns-prefetch", "stylesheet", "next",
+    "alternate", "preconnect", "icon",     "search",       nullptr};
+
 nsDOMTokenList* HTMLLinkElement::RelList() {
   if (!mRelList) {
-    if (Preferences::GetBool("network.preload")) {
+    auto preload = StaticPrefs::network_preload();
+    auto manifest = StaticPrefs::dom_manifest_enabled();
+    if (manifest && preload) {
+      mRelList = new nsDOMTokenList(this, nsGkAtoms::rel,
+                                    sSupportedRelValuesWithManifest);
+    } else if (manifest && !preload) {
+      mRelList = new nsDOMTokenList(this, nsGkAtoms::rel,
+                                    &sSupportedRelValuesWithManifest[1]);
+    } else if (!manifest && preload) {
       mRelList = new nsDOMTokenList(this, nsGkAtoms::rel, sSupportedRelValues);
-    } else {
+    } else {  // both false...drop preload
       mRelList =
           new nsDOMTokenList(this, nsGkAtoms::rel, &sSupportedRelValues[1]);
     }
@@ -418,7 +431,7 @@ already_AddRefed<nsIURI> HTMLLinkElement::GetHrefURI() const {
   return GetHrefURIForAnchors();
 }
 
-Maybe<nsStyleLinkElement::SheetInfo> HTMLLinkElement::GetStyleSheetInfo() {
+Maybe<LinkStyle::SheetInfo> HTMLLinkElement::GetStyleSheetInfo() {
   nsAutoString rel;
   GetAttr(kNameSpaceID_None, nsGkAtoms::rel, rel);
   uint32_t linkTypes = ParseLinkTypes(rel);
@@ -577,41 +590,41 @@ void HTMLLinkElement::
 
   uint32_t linkTypes = ParseLinkTypes(rel);
 
-  if ((linkTypes & ePREFETCH) || (linkTypes & eNEXT) ||
-      (linkTypes & ePRELOAD)) {
+  if ((linkTypes & ePREFETCH) || (linkTypes & eNEXT)) {
     nsCOMPtr<nsIPrefetchService> prefetchService(
         components::Prefetch::Service());
     if (prefetchService) {
       nsCOMPtr<nsIURI> uri(GetURI());
       if (uri) {
-        bool preload = !!(linkTypes & ePRELOAD);
-        nsContentPolicyType policyType;
-
-        if (preload) {
-          nsAttrValue asAttr;
-          nsAutoString mimeType;
-          nsAutoString media;
-          GetContentPolicyMimeTypeMedia(asAttr, policyType, mimeType, media);
-
-          if (policyType == nsIContentPolicy::TYPE_INVALID) {
-            // Ignore preload with a wrong or empty as attribute.
-            return;
-          }
-
-          if (!CheckPreloadAttrs(asAttr, mimeType, media, OwnerDoc())) {
-            policyType = nsIContentPolicy::TYPE_INVALID;
-          }
-        }
-
         auto referrerInfo = MakeRefPtr<ReferrerInfo>(*this);
-        if (preload) {
-          prefetchService->PreloadURI(uri, referrerInfo, this, policyType);
-        } else {
-          prefetchService->PrefetchURI(uri, referrerInfo, this,
-                                       linkTypes & ePREFETCH);
-        }
+        prefetchService->PrefetchURI(uri, referrerInfo, this,
+                                     linkTypes & ePREFETCH);
+        return;
+      }
+    }
+  }
+
+  if (linkTypes & ePRELOAD) {
+    nsCOMPtr<nsIURI> uri(GetURI());
+    if (uri) {
+      nsContentPolicyType policyType;
+
+      nsAttrValue asAttr;
+      nsAutoString mimeType;
+      nsAutoString media;
+      GetContentPolicyMimeTypeMedia(asAttr, policyType, mimeType, media);
+
+      if (policyType == nsIContentPolicy::TYPE_INVALID) {
+        // Ignore preload with a wrong or empty as attribute.
         return;
       }
+
+      if (!CheckPreloadAttrs(asAttr, mimeType, media, OwnerDoc())) {
+        policyType = nsIContentPolicy::TYPE_INVALID;
+      }
+
+      StartPreload(policyType);
+      return;
     }
   }
 
@@ -653,11 +666,6 @@ void HTMLLinkElement::UpdatePreload(nsAtom* aName, const nsAttrValue* aValue,
     return;
   }
 
-  nsCOMPtr<nsIPrefetchService> prefetchService(components::Prefetch::Service());
-  if (!prefetchService) {
-    return;
-  }
-
   nsCOMPtr<nsIURI> uri(GetURI());
   if (!uri) {
     return;
@@ -672,7 +680,7 @@ void HTMLLinkElement::UpdatePreload(nsAtom* aName, const nsAttrValue* aValue,
   if (asPolicyType == nsIContentPolicy::TYPE_INVALID) {
     // Ignore preload with a wrong or empty as attribute, but be sure to cancel
     // the old one.
-    prefetchService->CancelPrefetchPreloadURI(uri, this);
+    CancelPrefetchOrPreload();
     return;
   }
 
@@ -685,10 +693,8 @@ void HTMLLinkElement::UpdatePreload(nsAtom* aName, const nsAttrValue* aValue,
     CORSMode corsMode = AttrValueToCORSMode(aValue);
     CORSMode oldCorsMode = AttrValueToCORSMode(aOldValue);
     if (corsMode != oldCorsMode) {
-      prefetchService->CancelPrefetchPreloadURI(uri, this);
-
-      auto referrerInfo = MakeRefPtr<ReferrerInfo>(*this);
-      prefetchService->PreloadURI(uri, referrerInfo, this, policyType);
+      CancelPrefetchOrPreload();
+      StartPreload(policyType);
     }
     return;
   }
@@ -736,7 +742,7 @@ void HTMLLinkElement::UpdatePreload(nsAtom* aName, const nsAttrValue* aValue,
 
   if ((policyType != oldPolicyType) &&
       (oldPolicyType != nsIContentPolicy::TYPE_INVALID)) {
-    prefetchService->CancelPrefetchPreloadURI(uri, this);
+    CancelPrefetchOrPreload();
   }
 
   // Trigger a new preload if the policy type has changed.
@@ -744,12 +750,13 @@ void HTMLLinkElement::UpdatePreload(nsAtom* aName, const nsAttrValue* aValue,
   // trigger an error event.
   if ((policyType != oldPolicyType) ||
       (policyType == nsIContentPolicy::TYPE_INVALID)) {
-    auto referrerInfo = MakeRefPtr<ReferrerInfo>(*this);
-    prefetchService->PreloadURI(uri, referrerInfo, this, policyType);
+    StartPreload(policyType);
   }
 }
 
 void HTMLLinkElement::CancelPrefetchOrPreload() {
+  CancelPreload();
+
   nsCOMPtr<nsIPrefetchService> prefetchService(components::Prefetch::Service());
   if (prefetchService) {
     if (nsCOMPtr<nsIURI> uri = GetURI()) {
@@ -758,6 +765,25 @@ void HTMLLinkElement::CancelPrefetchOrPreload() {
   }
 }
 
+void HTMLLinkElement::StartPreload(nsContentPolicyType policyType) {
+  MOZ_ASSERT(!mPreload, "Forgot to cancel the running preload");
+
+  auto referrerInfo = MakeRefPtr<ReferrerInfo>(*this);
+  RefPtr<PreloaderBase> preload =
+      OwnerDoc()->Preloads().PreloadLinkElement(this, policyType, referrerInfo);
+  mPreload = preload.get();
+}
+
+void HTMLLinkElement::CancelPreload() {
+  if (mPreload) {
+    // This will cancel the loading channel if this was the last referred node
+    // and the preload is not used up until now to satisfy a regular tag load
+    // request.
+    mPreload->RemoveLinkPreloadNode(this);
+    mPreload = nullptr;
+  }
+}
+
 // We will use official mime-types from:
 // https://www.iana.org/assignments/media-types/media-types.xhtml#font
 // We do not support old deprecated mime-types for preload feature.
diff --git a/dom/html/HTMLLinkElement.h b/dom/html/HTMLLinkElement.h
index ea3861a2b9..46197c25be 100644
--- a/dom/html/HTMLLinkElement.h
+++ b/dom/html/HTMLLinkElement.h
@@ -7,8 +7,9 @@
 
 #include "mozilla/Attributes.h"
 #include "mozilla/dom/Link.h"
+#include "mozilla/dom/LinkStyle.h"
+#include "mozilla/WeakPtr.h"
 #include "nsGenericHTMLElement.h"
-#include "nsStyleLinkElement.h"
 #include "nsDOMTokenList.h"
 
 namespace mozilla {
@@ -19,7 +20,7 @@ namespace dom {
 // NOTE(emilio): If we stop inheriting from Link, we need to remove the
 // IsHTMLElement(nsGkAtoms::link) checks in Link.cpp.
 class HTMLLinkElement final : public nsGenericHTMLElement,
-                              public nsStyleLinkElement,
+                              public LinkStyle,
                               public Link {
  public:
   explicit HTMLLinkElement(
@@ -129,7 +130,7 @@ class HTMLLinkElement final : public nsGenericHTMLElement,
     }
     return mSizes;
   }
-  void GetType(DOMString& aValue) { GetHTMLAttr(nsGkAtoms::type, aValue); }
+  void GetType(nsAString& aValue) { GetHTMLAttr(nsGkAtoms::type, aValue); }
   void SetType(const nsAString& aType, ErrorResult& aRv) {
     SetHTMLAttr(nsGkAtoms::type, aType, aRv);
   }
@@ -159,6 +160,18 @@ class HTMLLinkElement final : public nsGenericHTMLElement,
   void GetReferrerPolicy(nsAString& aReferrer) {
     GetEnumAttr(nsGkAtoms::referrerpolicy, EmptyCString().get(), aReferrer);
   }
+  void GetImageSrcset(nsAString& aImageSrcset) {
+    GetHTMLAttr(nsGkAtoms::imagesrcset, aImageSrcset);
+  }
+  void SetImageSrcset(const nsAString& aImageSrcset, ErrorResult& aError) {
+    SetHTMLAttr(nsGkAtoms::imagesrcset, aImageSrcset, aError);
+  }
+  void GetImageSizes(nsAString& aImageSizes) {
+    GetHTMLAttr(nsGkAtoms::imagesizes, aImageSizes);
+  }
+  void SetImageSizes(const nsAString& aImageSizes, ErrorResult& aError) {
+    SetHTMLAttr(nsGkAtoms::imagesizes, aImageSizes, aError);
+  }
 
   CORSMode GetCORSMode() const {
     return AttrValueToCORSMode(GetParsedAttr(nsGkAtoms::crossorigin));
@@ -183,17 +196,27 @@ class HTMLLinkElement final : public nsGenericHTMLElement,
                      const nsAttrValue* aOldValue);
   void CancelPrefetchOrPreload();
 
+  void StartPreload(nsContentPolicyType policyType);
+  void CancelPreload();
+
   // Returns whether the type attribute specifies the text/css mime type for
   // link elements.
   static bool IsCSSMimeTypeAttributeForLinkElement(
       const mozilla::dom::Element&);
 
-  // nsStyleLinkElement
+  // LinkStyle
+  nsIContent& AsContent() final { return *this; }
+  const LinkStyle* AsLinkStyle() const final { return this; }
   Maybe<SheetInfo> GetStyleSheetInfo() final;
 
   RefPtr<nsDOMTokenList> mRelList;
   RefPtr<nsDOMTokenList> mSizes;
 
+  // A weak reference to our preload is held only to cancel the preload when
+  // this node updates or unbounds from the tree.  We want to prevent cycles,
+  // the preload is held alive by other means.
+  WeakPtr<PreloaderBase> mPreload;
+
   // The "explicitly enabled" flag. This flag is set whenever the `disabled`
   // attribute is explicitly unset, and makes alternate stylesheets not be
   // disabled by default anymore.
diff --git a/dom/html/HTMLMediaElement.cpp b/dom/html/HTMLMediaElement.cpp
index 4621f7fc31..bf4834ece4 100644
--- a/dom/html/HTMLMediaElement.cpp
+++ b/dom/html/HTMLMediaElement.cpp
@@ -79,6 +79,7 @@
 #include "mozilla/dom/power/PowerManagerService.h"
 #include "mozilla/net/UrlClassifierFeatureFactory.h"
 #include "nsAttrValueInlines.h"
+#include "nsComponentManagerUtils.h"
 #include "nsContentPolicyUtils.h"
 #include "nsContentUtils.h"
 #include "nsCycleCollectionParticipant.h"
@@ -133,8 +134,7 @@ using namespace mozilla::layers;
 using mozilla::net::nsMediaFragmentURIParser;
 using namespace mozilla::dom::HTMLMediaElement_Binding;
 
-namespace mozilla {
-namespace dom {
+namespace mozilla::dom {
 
 extern void NotifyMediaStarted(uint64_t aWindowID);
 extern void NotifyMediaStopped(uint64_t aWindowID);
@@ -7711,8 +7711,7 @@ void HTMLMediaElement::ClearResumeDelayedMediaPlaybackAgentIfNeeded() {
   }
 }
 
-}  // namespace dom
-}  // namespace mozilla
+}  // namespace mozilla::dom
 
 #undef LOG
 #undef LOG_EVENT
diff --git a/dom/html/HTMLMenuElement.cpp b/dom/html/HTMLMenuElement.cpp
index d94e5f74b2..5bd40d7217 100644
--- a/dom/html/HTMLMenuElement.cpp
+++ b/dom/html/HTMLMenuElement.cpp
@@ -11,6 +11,7 @@
 #include "mozilla/dom/HTMLMenuItemElement.h"
 #include "nsIMenuBuilder.h"
 #include "nsAttrValueInlines.h"
+#include "nsComponentManagerUtils.h"
 #include "nsContentUtils.h"
 #include "nsIURI.h"
 
@@ -18,8 +19,7 @@
 
 NS_IMPL_NS_NEW_HTML_ELEMENT(Menu)
 
-namespace mozilla {
-namespace dom {
+namespace mozilla::dom {
 
 enum MenuType : uint8_t { MENU_TYPE_CONTEXT = 1, MENU_TYPE_TOOLBAR };
 
@@ -211,5 +211,4 @@ JSObject* HTMLMenuElement::WrapNode(JSContext* aCx,
   return HTMLMenuElement_Binding::Wrap(aCx, this, aGivenProto);
 }
 
-}  // namespace dom
-}  // namespace mozilla
+}  // namespace mozilla::dom
diff --git a/dom/html/HTMLStyleElement.cpp b/dom/html/HTMLStyleElement.cpp
index 40d9e6f503..4278f42fee 100644
--- a/dom/html/HTMLStyleElement.cpp
+++ b/dom/html/HTMLStyleElement.cpp
@@ -28,17 +28,16 @@ NS_IMPL_CYCLE_COLLECTION_CLASS(HTMLStyleElement)
 
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(HTMLStyleElement,
                                                   nsGenericHTMLElement)
-  tmp->nsStyleLinkElement::Traverse(cb);
+  tmp->LinkStyle::Traverse(cb);
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
 
 NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(HTMLStyleElement,
                                                 nsGenericHTMLElement)
-  tmp->nsStyleLinkElement::Unlink();
+  tmp->LinkStyle::Unlink();
 NS_IMPL_CYCLE_COLLECTION_UNLINK_END
 
 NS_IMPL_ISUPPORTS_CYCLE_COLLECTION_INHERITED(HTMLStyleElement,
                                              nsGenericHTMLElement,
-                                             nsIStyleSheetLinkingElement,
                                              nsIMutationObserver)
 
 NS_IMPL_ELEMENT_CLONE(HTMLStyleElement)
@@ -161,7 +160,7 @@ void HTMLStyleElement::SetTextContentInternal(const nsAString& aTextContent,
   Unused << UpdateStyleSheetInternal(nullptr, nullptr);
 }
 
-Maybe<nsStyleLinkElement::SheetInfo> HTMLStyleElement::GetStyleSheetInfo() {
+Maybe<LinkStyle::SheetInfo> HTMLStyleElement::GetStyleSheetInfo() {
   if (!IsCSSMimeTypeAttributeForStyleElement(*this)) {
     return Nothing();
   }
diff --git a/dom/html/HTMLStyleElement.h b/dom/html/HTMLStyleElement.h
index 9725212e41..fc01b01e47 100644
--- a/dom/html/HTMLStyleElement.h
+++ b/dom/html/HTMLStyleElement.h
@@ -6,15 +6,15 @@
 #define mozilla_dom_HTMLStyleElement_h
 
 #include "mozilla/Attributes.h"
+#include "mozilla/dom/LinkStyle.h"
 #include "nsGenericHTMLElement.h"
-#include "nsStyleLinkElement.h"
 #include "nsStubMutationObserver.h"
 
 namespace mozilla {
 namespace dom {
 
 class HTMLStyleElement final : public nsGenericHTMLElement,
-                               public nsStyleLinkElement,
+                               public LinkStyle,
                                public nsStubMutationObserver {
  public:
   explicit HTMLStyleElement(
@@ -69,6 +69,8 @@ class HTMLStyleElement final : public nsGenericHTMLElement,
  protected:
   virtual ~HTMLStyleElement();
 
+  nsIContent& AsContent() final { return *this; }
+  const LinkStyle* AsLinkStyle() const final { return this; }
   Maybe<SheetInfo> GetStyleSheetInfo() final;
 
   /**
diff --git a/dom/html/HTMLTrackElement.cpp b/dom/html/HTMLTrackElement.cpp
index c8c615ada3..0f0fd58ae2 100644
--- a/dom/html/HTMLTrackElement.cpp
+++ b/dom/html/HTMLTrackElement.cpp
@@ -28,8 +28,10 @@
 #include "nsThreadUtils.h"
 #include "nsVideoFrame.h"
 
-static mozilla::LazyLogModule gTrackElementLog("nsTrackElement");
-#define LOG(type, msg) MOZ_LOG(gTrackElementLog, type, msg)
+extern mozilla::LazyLogModule gTextTrackLog;
+#define LOG(msg, ...)                       \
+  MOZ_LOG(gTextTrackLog, LogLevel::Verbose, \
+          ("TextTrackElement=%p, " msg, this, ##__VA_ARGS__))
 
 // Replace the usual NS_IMPL_NS_NEW_HTML_ELEMENT(Track) so
 // we can return an UnknownElement instead when pref'd off.
@@ -90,7 +92,7 @@ class WindowDestroyObserver final : public nsIObserver {
       NS_ENSURE_SUCCESS(rv, rv);
       if (innerID == mInnerID) {
         if (mTrackElement) {
-          mTrackElement->NotifyShutdown();
+          mTrackElement->CancelChannelAndListener();
         }
         UnRegisterWindowDestroyObserver();
       }
@@ -125,7 +127,7 @@ HTMLTrackElement::~HTMLTrackElement() {
   if (mWindowDestroyObserver) {
     mWindowDestroyObserver->UnRegisterWindowDestroyObserver();
   }
-  NotifyShutdown();
+  CancelChannelAndListener();
 }
 
 NS_IMPL_ELEMENT_CLONE(HTMLTrackElement)
@@ -203,18 +205,20 @@ bool HTMLTrackElement::ParseAttribute(int32_t aNamespaceID, nsAtom* aAttribute,
 }
 
 void HTMLTrackElement::SetSrc(const nsAString& aSrc, ErrorResult& aError) {
+  LOG("Set src=%s", NS_ConvertUTF16toUTF8(aSrc).get());
+
+  nsAutoString src;
+  if (GetAttr(kNameSpaceID_None, nsGkAtoms::src, src) && src == aSrc) {
+    LOG("No need to reload for same src url");
+    return;
+  }
+
   SetHTMLAttr(nsGkAtoms::src, aSrc, aError);
-  uint16_t oldReadyState = ReadyState();
   SetReadyState(TextTrackReadyState::NotLoaded);
   if (!mMediaParent) {
     return;
   }
-  if (mTrack && (oldReadyState != TextTrackReadyState::NotLoaded)) {
-    // Remove all the cues in MediaElement.
-    mMediaParent->RemoveTextTrack(mTrack);
-    // Recreate mTrack.
-    CreateTextTrack();
-  }
+
   // Stop WebVTTListener.
   mListener = nullptr;
   if (mChannel) {
@@ -222,10 +226,45 @@ void HTMLTrackElement::SetSrc(const nsAString& aSrc, ErrorResult& aError) {
     mChannel = nullptr;
   }
 
-  DispatchLoadResource();
+  MaybeDispatchLoadResource();
+}
+
+void HTMLTrackElement::MaybeClearAllCues() {
+  // Empty track's cue list whenever the track element's `src` attribute set,
+  // changed, or removed,
+  // https://html.spec.whatwg.org/multipage/media.html#sourcing-out-of-band-text-tracks:attr-track-src
+  if (!mTrack) {
+    return;
+  }
+  mTrack->ClearAllCues();
 }
 
-void HTMLTrackElement::DispatchLoadResource() {
+// This function will run partial steps from `start-the-track-processing-model`
+// and finish the rest of steps in `LoadResource()` during the stable state.
+// https://html.spec.whatwg.org/multipage/media.html#start-the-track-processing-model
+void HTMLTrackElement::MaybeDispatchLoadResource() {
+  MOZ_ASSERT(mTrack, "Should have already created text track!");
+
+  // step2, if the text track's text track mode is not set to one of hidden or
+  // showing, then return.
+  if (mTrack->Mode() == TextTrackMode::Disabled) {
+    LOG("Do not load resource for disable track");
+    return;
+  }
+
+  // step3, if the text track's track element does not have a media element as a
+  // parent, return.
+  if (!mMediaParent) {
+    LOG("Do not load resource for track without media element");
+    return;
+  }
+
+  if (ReadyState() == TextTrackReadyState::Loaded) {
+    LOG("Has already loaded resource");
+    return;
+  }
+
+  // step5, await a stable state and run the rest of steps.
   if (!mLoadResourceDispatched) {
     RefPtr<WebVTTListener> listener = new WebVTTListener(this);
     RefPtr<Runnable> r = NewRunnableMethod<RefPtr<WebVTTListener>>(
@@ -237,24 +276,22 @@ void HTMLTrackElement::DispatchLoadResource() {
 }
 
 void HTMLTrackElement::LoadResource(RefPtr<WebVTTListener>&& aWebVTTListener) {
+  LOG("LoadResource");
   mLoadResourceDispatched = false;
 
-  // Find our 'src' url
   nsAutoString src;
-  if (!GetAttr(kNameSpaceID_None, nsGkAtoms::src, src)) {
+  if (!GetAttr(kNameSpaceID_None, nsGkAtoms::src, src) || src.IsEmpty()) {
+    LOG("Fail to load because no src");
+    SetReadyState(TextTrackReadyState::FailedToLoad);
     return;
   }
 
   nsCOMPtr<nsIURI> uri;
   nsresult rv = NewURIFromString(src, getter_AddRefs(uri));
   NS_ENSURE_TRUE_VOID(NS_SUCCEEDED(rv));
-  LOG(LogLevel::Info, ("%p Trying to load from src=%s", this,
-                       NS_ConvertUTF16toUTF8(src).get()));
+  LOG("Trying to load from src=%s", NS_ConvertUTF16toUTF8(src).get());
 
-  if (mChannel) {
-    mChannel->Cancel(NS_BINDING_ABORTED);
-    mChannel = nullptr;
-  }
+  CancelChannelAndListener();
 
   // According to
   // https://www.w3.org/TR/html5/embedded-content-0.html#sourcing-out-of-band-text-tracks
@@ -295,32 +332,35 @@ void HTMLTrackElement::LoadResource(RefPtr<WebVTTListener>&& aWebVTTListener) {
   // 9. End the synchronous section, continuing the remaining steps in parallel.
   nsCOMPtr<nsIRunnable> runnable = NS_NewRunnableFunction(
       "dom::HTMLTrackElement::LoadResource",
-      [self = RefPtr<HTMLTrackElement>(this), uri, secFlags]() {
-        if (!self->mListener) {
+      [self = RefPtr<HTMLTrackElement>(this), this, uri, secFlags]() {
+        if (!mListener) {
           // Shutdown got called, abort.
           return;
         }
         nsCOMPtr<nsIChannel> channel;
-        nsCOMPtr<nsILoadGroup> loadGroup =
-            self->OwnerDoc()->GetDocumentLoadGroup();
+        nsCOMPtr<nsILoadGroup> loadGroup = OwnerDoc()->GetDocumentLoadGroup();
         nsresult rv = NS_NewChannel(getter_AddRefs(channel), uri,
-                                    static_cast<Element*>(self), secFlags,
+                                    static_cast<Element*>(this), secFlags,
                                     nsIContentPolicy::TYPE_INTERNAL_TRACK,
                                     nullptr,  // PerformanceStorage
                                     loadGroup);
 
-        NS_ENSURE_TRUE_VOID(NS_SUCCEEDED(rv));
+        if (NS_FAILED(rv)) {
+          LOG("create channel failed.");
+          SetReadyState(TextTrackReadyState::FailedToLoad);
+          return;
+        }
 
-        channel->SetNotificationCallbacks(self->mListener);
+        channel->SetNotificationCallbacks(mListener);
 
-        LOG(LogLevel::Debug, ("opening webvtt channel"));
-        rv = channel->AsyncOpen(self->mListener);
+        LOG("opening webvtt channel");
+        rv = channel->AsyncOpen(mListener);
 
         if (NS_FAILED(rv)) {
-          self->SetReadyState(TextTrackReadyState::FailedToLoad);
+          SetReadyState(TextTrackReadyState::FailedToLoad);
           return;
         }
-        self->mChannel = channel;
+        mChannel = channel;
       });
   doc->Dispatch(TaskCategory::Other, runnable.forget());
 }
@@ -329,7 +369,7 @@ nsresult HTMLTrackElement::BindToTree(BindContext& aContext, nsINode& aParent) {
   nsresult rv = nsGenericHTMLElement::BindToTree(aContext, aParent);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  LOG(LogLevel::Debug, ("Track Element bound to tree."));
+  LOG("Track Element bound to tree.");
   auto* parent = HTMLMediaElement::FromNode(aParent);
   if (!parent) {
     return NS_OK;
@@ -341,7 +381,7 @@ nsresult HTMLTrackElement::BindToTree(BindContext& aContext, nsINode& aParent) {
 
     // TODO: separate notification for 'alternate' tracks?
     mMediaParent->NotifyAddedSource();
-    LOG(LogLevel::Debug, ("Track element sent notification to parent."));
+    LOG("Track element sent notification to parent.");
 
     // We may already have a TextTrack at this point if GetTrack() has already
     // been called. This happens, for instance, if script tries to get the
@@ -349,7 +389,7 @@ nsresult HTMLTrackElement::BindToTree(BindContext& aContext, nsINode& aParent) {
     if (!mTrack) {
       CreateTextTrack();
     }
-    DispatchLoadResource();
+    MaybeDispatchLoadResource();
   }
 
   return NS_OK;
@@ -385,9 +425,11 @@ void HTMLTrackElement::SetReadyState(uint16_t aReadyState) {
   if (mTrack) {
     switch (aReadyState) {
       case TextTrackReadyState::Loaded:
+        LOG("dispatch 'load' event");
         DispatchTrackRunnable(NS_LITERAL_STRING("load"));
         break;
       case TextTrackReadyState::FailedToLoad:
+        LOG("dispatch 'error' event");
         DispatchTrackRunnable(NS_LITERAL_STRING("error"));
         break;
     }
@@ -415,14 +457,36 @@ void HTMLTrackElement::DispatchTrustedEvent(const nsAString& aName) {
                                        aName, CanBubble::eNo, Cancelable::eNo);
 }
 
-void HTMLTrackElement::DropChannel() { mChannel = nullptr; }
-
-void HTMLTrackElement::NotifyShutdown() {
+void HTMLTrackElement::CancelChannelAndListener() {
   if (mChannel) {
     mChannel->Cancel(NS_BINDING_ABORTED);
+    mChannel->SetNotificationCallbacks(nullptr);
+    mChannel = nullptr;
   }
-  mChannel = nullptr;
-  mListener = nullptr;
+
+  if (mListener) {
+    mListener->Cancel();
+    mListener = nullptr;
+  }
+}
+
+nsresult HTMLTrackElement::AfterSetAttr(int32_t aNameSpaceID, nsAtom* aName,
+                                        const nsAttrValue* aValue,
+                                        const nsAttrValue* aOldValue,
+                                        nsIPrincipal* aMaybeScriptedPrincipal,
+                                        bool aNotify) {
+  if (aNameSpaceID == kNameSpaceID_None && aName == nsGkAtoms::src) {
+    MaybeClearAllCues();
+    // In spec, `start the track processing model` step10, while fetching is
+    // ongoing, if the track URL changes, then we have to set the `FailedToLoad`
+    // state.
+    // https://html.spec.whatwg.org/multipage/media.html#sourcing-out-of-band-text-tracks:text-track-failed-to-load-3
+    if (ReadyState() == TextTrackReadyState::Loading && aValue != aOldValue) {
+      SetReadyState(TextTrackReadyState::FailedToLoad);
+    }
+  }
+  return nsGenericHTMLElement::AfterSetAttr(
+      aNameSpaceID, aName, aValue, aOldValue, aMaybeScriptedPrincipal, aNotify);
 }
 
 }  // namespace dom
diff --git a/dom/html/HTMLTrackElement.h b/dom/html/HTMLTrackElement.h
index faea1dacb1..18c03ffd30 100644
--- a/dom/html/HTMLTrackElement.h
+++ b/dom/html/HTMLTrackElement.h
@@ -83,12 +83,19 @@ class HTMLTrackElement final : public nsGenericHTMLElement {
   virtual nsresult BindToTree(BindContext&, nsINode& aParent) override;
   virtual void UnbindFromTree(bool aNullParent) override;
 
+  virtual nsresult AfterSetAttr(int32_t aNameSpaceID, nsAtom* aName,
+                                const nsAttrValue* aValue,
+                                const nsAttrValue* aOldValue,
+                                nsIPrincipal* aMaybeScriptedPrincipal,
+                                bool aNotify) override;
+
   void DispatchTrackRunnable(const nsString& aEventName);
   void DispatchTrustedEvent(const nsAString& aName);
 
-  void DropChannel();
+  void CancelChannelAndListener();
 
-  void NotifyShutdown();
+  // Only load resource for the non-disabled track with media parent.
+  void MaybeDispatchLoadResource();
 
  protected:
   virtual ~HTMLTrackElement();
@@ -109,12 +116,13 @@ class HTMLTrackElement final : public nsGenericHTMLElement {
   void CreateTextTrack();
 
  private:
-  void DispatchLoadResource();
   // Open a new channel to the HTMLTrackElement's src attribute and call
   // mListener's LoadResource().
   void LoadResource(RefPtr<WebVTTListener>&& aWebVTTListener);
   bool mLoadResourceDispatched;
 
+  void MaybeClearAllCues();
+
   RefPtr<WindowDestroyObserver> mWindowDestroyObserver;
 };
 
diff --git a/dom/html/TextTrackManager.cpp b/dom/html/TextTrackManager.cpp
index 9053720764..3a452acae4 100644
--- a/dom/html/TextTrackManager.cpp
+++ b/dom/html/TextTrackManager.cpp
@@ -163,7 +163,7 @@ already_AddRefed<TextTrack> TextTrackManager::AddTextTrack(
     RefPtr<nsIRunnable> task = NewRunnableMethod(
         "dom::TextTrackManager::HonorUserPreferencesForTrackSelection", this,
         &TextTrackManager::HonorUserPreferencesForTrackSelection);
-    nsContentUtils::RunInStableState(task.forget());
+    NS_DispatchToMainThread(task.forget());
   }
 
   return track.forget();
@@ -182,7 +182,7 @@ void TextTrackManager::AddTextTrack(TextTrack* aTextTrack) {
     RefPtr<nsIRunnable> task = NewRunnableMethod(
         "dom::TextTrackManager::HonorUserPreferencesForTrackSelection", this,
         &TextTrackManager::HonorUserPreferencesForTrackSelection);
-    nsContentUtils::RunInStableState(task.forget());
+    NS_DispatchToMainThread(task.forget());
   }
 }
 
diff --git a/dom/html/moz.build b/dom/html/moz.build
index ea9c9cf93c..b9512eaa25 100644
--- a/dom/html/moz.build
+++ b/dom/html/moz.build
@@ -8,6 +8,7 @@ with Files("**"):
 DIRS += ['input']
 
 MOCHITEST_MANIFESTS += [
+    'test/dialog/mochitest.ini',
     'test/forms/mochitest.ini',
     'test/mochitest.ini',
 ]
diff --git a/dom/html/nsHTMLContentSink.cpp b/dom/html/nsHTMLContentSink.cpp
index 2e5db7b3e3..55c273d491 100644
--- a/dom/html/nsHTMLContentSink.cpp
+++ b/dom/html/nsHTMLContentSink.cpp
@@ -46,11 +46,9 @@
 #include "nsIScriptGlobalObject.h"
 #include "nsNameSpaceManager.h"
 
-#include "nsIStyleSheetLinkingElement.h"
 #include "nsError.h"
 #include "nsContentPolicyUtils.h"
 #include "nsIScriptContext.h"
-#include "nsStyleLinkElement.h"
 
 #include "nsLayoutCID.h"
 
diff --git a/dom/html/test/dialog/mochitest.ini b/dom/html/test/dialog/mochitest.ini
new file mode 100644
index 0000000000..7a0cbd1a7a
--- /dev/null
+++ b/dom/html/test/dialog/mochitest.ini
@@ -0,0 +1,7 @@
+[DEFAULT]
+prefs =
+  dom.dialog_element.enabled=true
+[test_cancelDialogByEscape.html]
+[test_dialog_cancel_events.html]
+[test_dialog_cancel_preventDefault.html]
+[test_dialog_keydown_preventDefault.html]
diff --git a/dom/html/test/dialog/test_cancelDialogByEscape.html b/dom/html/test/dialog/test_cancelDialogByEscape.html
new file mode 100644
index 0000000000..0dccf2146e
--- /dev/null
+++ b/dom/html/test/dialog/test_cancelDialogByEscape.html
@@ -0,0 +1,63 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1322947
+-->
+<head>
+  <title>Test for Bug 1322947</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/EventUtils.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body onload="SimpleTest.waitForFocus(runTest)">
+  <a target="_blank"
+    href="https://bugzilla.mozilla.org/show_bug.cgi?id=1322947"> Test dialog modal is closed by escape key</a>
+<p id="display"></p>
+<dialog id="dialog">
+  <p>Hello World</p>
+</dialog>
+
+<dialog id="dialogWithAutofocus">
+  <input autofocus/>
+</dialog>
+
+<pre id="test">
+<script type="application/javascript">
+SimpleTest.waitForExplicitFinish();
+
+/* Make sure we still cancel the dialog even if the input element is focused */
+function runTestCancelWhenInputFocused() {
+  const dialog = document.getElementById("dialogWithAutofocus");
+  const input = document.querySelector("input");
+
+  dialog.addEventListener("close", function() {
+    ok(dialog.close, "dialog with input autofocused is closed");
+    done();
+  });
+  dialog.showModal();
+  ok(input == document.activeElement, "input element should be focused");
+
+  synthesizeKey("VK_ESCAPE", {}, window);
+}
+
+function runTest() {
+  const dialog = document.getElementById("dialog");
+
+  dialog.addEventListener("close", function() {
+    ok(dialog.close, "dialog closed");
+    setTimeout(function(){
+      runTestCancelWhenInputFocused();
+    }, 0);
+  });
+
+  dialog.showModal();
+  synthesizeKey("VK_ESCAPE", {}, window);
+}
+
+function done() {
+  SimpleTest.finish();
+}
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/html/test/dialog/test_dialog_cancel_events.html b/dom/html/test/dialog/test_dialog_cancel_events.html
new file mode 100644
index 0000000000..8e404ba6c2
--- /dev/null
+++ b/dom/html/test/dialog/test_dialog_cancel_events.html
@@ -0,0 +1,56 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1322947
+-->
+<head>
+  <title>Test for Bug 1322947</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/EventUtils.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body onload="runTest()">
+  <a target="_blank"
+    href="https://bugzilla.mozilla.org/show_bug.cgi?id=1322947">Test cancel event
+  is fired when the dialog is closed by user interaction</a>
+<p id="display"></p>
+<dialog>
+  <p>Hello World</p>
+</dialog>
+<pre id="test">
+<script type="application/javascript">
+SimpleTest.waitForExplicitFinish();
+
+var hasCancelEventFired = false;
+var hasCloseEventFired = false;
+
+function runTest() {
+  const dialog = document.querySelector("dialog");
+
+  dialog.addEventListener("cancel", function(event) {
+    ok(true, "cancel event is fired");
+    ok(event.cancelable, "cancel event should be cancelable");
+    ok(!hasCancelEventFired, "cancel event should only be fired once");
+    ok(!hasCloseEventFired, "close event should be fired after cancel event");
+    hasCancelEventFired = true;
+  });
+
+  dialog.addEventListener("close", function() {
+    ok(true, "close event is fired");
+    ok(!hasCloseEventFired, "close event should only be fired once");
+    ok(hasCancelEventFired, "cancel event should be fired before close event");
+    hasCloseEventFired = true;
+    done();
+  });
+
+  dialog.showModal();
+  synthesizeKey("VK_ESCAPE", {}, window);
+}
+
+function done() {
+  SimpleTest.finish();
+}
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/html/test/dialog/test_dialog_cancel_preventDefault.html b/dom/html/test/dialog/test_dialog_cancel_preventDefault.html
new file mode 100644
index 0000000000..3cc4dd0eee
--- /dev/null
+++ b/dom/html/test/dialog/test_dialog_cancel_preventDefault.html
@@ -0,0 +1,56 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1322947
+-->
+<head>
+  <title>Test for Bug 1322947</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/EventUtils.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body onload="SimpleTest.waitForFocus(runTest)">
+  <a target="_blank"
+    href="https://bugzilla.mozilla.org/show_bug.cgi?id=1322947">Test cancel event with preventDefault on cancel event for dialog element</a>
+<p id="display"></p>
+<dialog>
+  <p>Hello World</p>
+</dialog>
+<pre id="test">
+<script type="application/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+var hasCancelEventFired = false;
+
+function runTest() {
+  const dialog = document.querySelector("dialog");
+
+  const verify = () => {
+    ok(hasCancelEventFired, "cancel is fired");
+    done();
+  }
+
+  dialog.addEventListener("cancel", function(event) {
+    hasCancelEventFired = true;
+    event.preventDefault();
+    setTimeout(function() {
+      verify();
+    }, 0)
+  });
+
+  dialog.addEventListener("close", function() {
+    ok(false, "close event should not be fired");
+  });
+
+  dialog.showModal();
+  synthesizeKey("VK_ESCAPE", {}, window);
+}
+
+function done() {
+  SimpleTest.finish();
+}
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/html/test/dialog/test_dialog_keydown_preventDefault.html b/dom/html/test/dialog/test_dialog_keydown_preventDefault.html
new file mode 100644
index 0000000000..8a9e1ecadc
--- /dev/null
+++ b/dom/html/test/dialog/test_dialog_keydown_preventDefault.html
@@ -0,0 +1,56 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1322947
+-->
+<head>
+  <title>Test for Bug 1322947</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/EventUtils.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body onload="SimpleTest.waitForFocus(runTest)">
+  <a target="_blank"
+    href="https://bugzilla.mozilla.org/show_bug.cgi?id=1322947">Test cancel event with preventDefault on keydown event for dialog element</a>
+<p id="display"></p>
+<dialog>
+  <p>Hello World</p>
+</dialog>
+<pre id="test">
+<script type="application/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+var hasCancelEventFired = false;
+
+function runTest() {
+  const dialog = document.querySelector("dialog");
+
+  const verify = () => {
+    ok(!hasCancelEventFired, "cancel should not be fired");
+    ok(hasKeydownEventFired, "document level keydown event should be fired");
+    done();
+  }
+
+  dialog.addEventListener("cancel", function(event) {
+    hasCancelEventFired = true;
+  });
+
+  document.addEventListener("keydown", function(event) {
+    hasKeydownEventFired = true;
+    event.preventDefault();
+    setTimeout(function() {
+      verify();
+    }, 0);
+  });
+  dialog.showModal();
+  synthesizeKey("VK_ESCAPE", {}, window);
+}
+
+function done() {
+  SimpleTest.finish();
+}
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/html/test/file_cookiemanager.js b/dom/html/test/file_cookiemanager.js
index 7a57709bd9..913b2c4056 100644
--- a/dom/html/test/file_cookiemanager.js
+++ b/dom/html/test/file_cookiemanager.js
@@ -2,7 +2,7 @@ addMessageListener("getCookieFromManager", ({ host, path }) => {
   let cm = Cc["@mozilla.org/cookiemanager;1"].getService(Ci.nsICookieManager);
   let values = [];
   path = path.substring(0, path.lastIndexOf("/"));
-  for (let cookie of cm.enumerator) {
+  for (let cookie of cm.cookies) {
     if (!cookie) {
       break;
     }
diff --git a/dom/ipc/ContentParent.cpp b/dom/ipc/ContentParent.cpp
index 5da8eaa50a..abe3951438 100644
--- a/dom/ipc/ContentParent.cpp
+++ b/dom/ipc/ContentParent.cpp
@@ -12,6 +12,8 @@
 #include "BrowserParent.h"
 #include "mozilla/dom/MediaControlService.h"
 
+#include "mozilla/XREAppData.h"
+
 #if defined(ANDROID) || defined(LINUX)
 #  include <sys/time.h>
 #  include <sys/resource.h>
diff --git a/dom/ipc/WindowGlobalChild.cpp b/dom/ipc/WindowGlobalChild.cpp
index ea45b96ba4..b6d77c9f01 100644
--- a/dom/ipc/WindowGlobalChild.cpp
+++ b/dom/ipc/WindowGlobalChild.cpp
@@ -20,6 +20,7 @@
 #include "nsFrameLoaderOwner.h"
 #include "nsGlobalWindowInner.h"
 #include "nsFrameLoaderOwner.h"
+#include "nsNetUtil.h"
 #include "nsQueryObject.h"
 
 #include "mozilla/dom/JSWindowActorBinding.h"
diff --git a/dom/locales/en-US/chrome/security/csp.properties b/dom/locales/en-US/chrome/security/csp.properties
index f4b1f0f0dc..acf3dc8ffc 100644
--- a/dom/locales/en-US/chrome/security/csp.properties
+++ b/dom/locales/en-US/chrome/security/csp.properties
@@ -59,15 +59,6 @@ reportURInotInReportOnlyHeader = This site (%1$S) has a Report-Only policy witho
 # LOCALIZATION NOTE (failedToParseUnrecognizedSource):
 # %1$S is the CSP Source that could not be parsed
 failedToParseUnrecognizedSource = Failed to parse unrecognized source %1$S
-# LOCALIZATION NOTE (inlineScriptBlocked):
-# inline script refers to JavaScript code that is embedded into the HTML document.
-inlineScriptBlocked = An attempt to execute inline scripts has been blocked
-# LOCALIZATION NOTE (inlineStyleBlocked):
-# inline style refers to CSS code that is embedded into the HTML document.
-inlineStyleBlocked = An attempt to apply inline style sheets has been blocked
-# LOCALIZATION NOTE (scriptFromStringBlocked):
-# eval is a name and should not be localized.
-scriptFromStringBlocked = An attempt to call JavaScript from a string (by calling a function like eval) has been blocked
 # LOCALIZATION NOTE (upgradeInsecureRequest):
 # %1$S is the URL of the upgraded request; %2$S is the upgraded scheme.
 upgradeInsecureRequest = Upgrading insecure request ‘%1$S’ to use ‘%2$S’
@@ -88,9 +79,6 @@ ignoringDirectiveWithNoValues = Ignoring ‘%1$S’ since it does not contain an
 # LOCALIZATION NOTE (ignoringReportOnlyDirective):
 # %1$S is the directive that is ignored in report-only mode.
 ignoringReportOnlyDirective = Ignoring sandbox directive when delivered in a report-only policy ‘%1$S’
-# LOCALIZATION NOTE (deprecatedReferrerDirective):
-# %1$S is the value of the deprecated Referrer Directive.
-deprecatedReferrerDirective = Referrer Directive ‘%1$S’ has been deprecated. Please use the Referrer-Policy header instead.
 # LOCALIZATION NOTE (IgnoringSrcBecauseOfDirective):
 # %1$S is the name of the src that is ignored.
 # %2$S is the name of the directive that causes the src to be ignored.
@@ -103,19 +91,12 @@ couldntParseInvalidSource = Couldn’t parse invalid source %1$S
 # LOCALIZATION NOTE (couldntParseInvalidHost):
 # %1$S is the host that's invalid
 couldntParseInvalidHost = Couldn’t parse invalid host %1$S
-# LOCALIZATION NOTE (couldntParseScheme):
-# %1$S is the string source
-couldntParseScheme = Couldn’t parse scheme in %1$S
 # LOCALIZATION NOTE (couldntParsePort):
 # %1$S is the string source
 couldntParsePort = Couldn’t parse port in %1$S
 # LOCALIZATION NOTE (duplicateDirective):
 # %1$S is the name of the duplicate directive
 duplicateDirective = Duplicate %1$S directives detected.  All but the first instance will be ignored.
-# LOCALIZATION NOTE (deprecatedChildSrcDirective):
-# %1$S is the value of the deprecated directive.
-# Do not localize: worker-src, frame-src
-deprecatedChildSrcDirective = Directive ‘%1$S’ has been deprecated. Please use directive ‘worker-src’ to control workers, or directive ‘frame-src’ to control frames respectively.
 # LOCALIZATION NOTE (couldntParseInvalidSandboxFlag):
 # %1$S is the option that could not be understood
 couldntParseInvalidSandboxFlag = Couldn’t parse invalid sandbox flag ‘%1$S’
diff --git a/dom/localstorage/ActorsParent.cpp b/dom/localstorage/ActorsParent.cpp
index 344ccdec9a..87914a4030 100644
--- a/dom/localstorage/ActorsParent.cpp
+++ b/dom/localstorage/ActorsParent.cpp
@@ -5931,8 +5931,8 @@ void Snapshot::SaveItem(const nsAString& aKey, const LSValue& aOldValue,
   }
 
   if (!mLoadedItems.GetEntry(aKey) && !mUnknownItems.GetEntry(aKey)) {
-    LSValue oldValue(aOldValue);
-    mValues.LookupForAdd(aKey).OrInsert([oldValue]() { return oldValue; });
+    mValues.WithEntryHandle(aKey,
+                            [&](auto&& entry) { entry.OrInsert(aOldValue); });
   }
 
   if (aAffectsOrder && !mSavedKeys) {
diff --git a/dom/localstorage/LSSnapshot.cpp b/dom/localstorage/LSSnapshot.cpp
index b15a523f69..df6e83161f 100644
--- a/dom/localstorage/LSSnapshot.cpp
+++ b/dom/localstorage/LSSnapshot.cpp
@@ -697,14 +697,14 @@ nsresult LSSnapshot::GetItemInternal(const nsAString& aKey,
       if (aValue.WasPassed()) {
         const nsString& value = aValue.Value();
         if (!value.IsVoid()) {
-          auto entry = mValues.LookupForAdd(aKey);
-          if (entry) {
-            result = entry.Data();
-            entry.Data() = value;
-          } else {
-            result.SetIsVoid(true);
-            entry.OrInsert([value]() { return value; });
-          }
+          mValues.WithEntryHandle(aKey, [&](auto&& entry) {
+            if (entry) {
+              result = std::exchange(entry.Data(), value);
+            } else {
+              result.SetIsVoid(true);
+              entry.Insert(value);
+            }
+          });
         } else {
           if (auto entry = mValues.Lookup(aKey)) {
             result = entry.Data();
diff --git a/dom/manifest/test/mochitest.ini b/dom/manifest/test/mochitest.ini
index b7e389c434..e8a7fbc5c7 100644
--- a/dom/manifest/test/mochitest.ini
+++ b/dom/manifest/test/mochitest.ini
@@ -8,6 +8,7 @@ support-files =
 [test_ImageObjectProcessor_sizes.html]
 [test_ImageObjectProcessor_src.html]
 [test_ImageObjectProcessor_type.html]
+[test_link_relList_supports_manifest.html]
 [test_ManifestProcessor_background_color.html]
 [test_ManifestProcessor_dir.html]
 [test_ManifestProcessor_display.html]
@@ -20,4 +21,4 @@ support-files =
 [test_ManifestProcessor_start_url.html]
 [test_ManifestProcessor_theme_color.html]
 [test_ManifestProcessor_warnings.html]
-[test_window_onappinstalled_event.html]
+[test_window_onappinstalled_event.html]
\ No newline at end of file
diff --git a/dom/manifest/test/test_link_relList_supports_manifest.html b/dom/manifest/test/test_link_relList_supports_manifest.html
new file mode 100644
index 0000000000..af678ddb5f
--- /dev/null
+++ b/dom/manifest/test/test_link_relList_supports_manifest.html
@@ -0,0 +1,47 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1596040
+-->
+
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 1596040 - Link relList support returns false for manifest</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css">
+  <script>
+  "use strict";
+  SimpleTest.waitForExplicitFinish();
+
+  async function run() {
+    const prefSetting = [
+      { manifest: true, preload: true },
+      { manifest: true, preload: false },
+      { manifest: false, preload: true },
+      { manifest: false, preload: false },
+    ];
+    for (const { manifest, preload } of prefSetting) {
+      await SpecialPowers.pushPrefEnv({
+        set: [
+          ["dom.manifest.enabled", manifest],
+          ["network.preload", preload],
+        ],
+      });
+      const { relList } = document.createElement("link");
+      is(
+        relList.supports("manifest"),
+        manifest,
+        `Expected manifest to be ${manifest}`
+      );
+      is(
+        relList.supports("preload"),
+        preload,
+        `Expected preload to be ${preload}`
+      );
+    }
+  }
+  run()
+    .catch(console.error)
+    .finally(() => SimpleTest.finish());
+  </script>
+</head>
diff --git a/dom/media/TextTrack.cpp b/dom/media/TextTrack.cpp
index 423d0d44d4..dd04f56eff 100644
--- a/dom/media/TextTrack.cpp
+++ b/dom/media/TextTrack.cpp
@@ -52,6 +52,24 @@ static const char* ToReadyStateStr(const TextTrackReadyState aState) {
   return "Unknown";
 }
 
+static const char* ToTextTrackKindStr(const TextTrackKind aKind) {
+  switch (aKind) {
+    case TextTrackKind::Subtitles:
+      return "Subtitles";
+    case TextTrackKind::Captions:
+      return "Captions";
+    case TextTrackKind::Descriptions:
+      return "Descriptions";
+    case TextTrackKind::Chapters:
+      return "Chapters";
+    case TextTrackKind::Metadata:
+      return "Metadata";
+    default:
+      MOZ_ASSERT_UNREACHABLE("Invalid kind.");
+  }
+  return "Unknown";
+}
+
 NS_IMPL_CYCLE_COLLECTION_INHERITED(TextTrack, DOMEventTargetHelper, mCueList,
                                    mActiveCueList, mTextTrackList,
                                    mTrackElement)
@@ -110,7 +128,8 @@ void TextTrack::SetMode(TextTrackMode aValue) {
   if (mMode == aValue) {
     return;
   }
-  WEBVTT_LOG("Set mode=%s", ToStateStr(aValue));
+  WEBVTT_LOG("Set mode=%s for track kind %s", ToStateStr(aValue),
+             ToTextTrackKindStr(mKind));
   mMode = aValue;
 
   HTMLMediaElement* mediaElement = GetMediaElement();
@@ -127,6 +146,12 @@ void TextTrack::SetMode(TextTrackMode aValue) {
   if (mediaElement) {
     mediaElement->NotifyTextTrackModeChanged();
   }
+  // https://html.spec.whatwg.org/multipage/media.html#sourcing-out-of-band-text-tracks:start-the-track-processing-model
+  // Run the `start-the-track-processing-model` to track's corresponding track
+  // element whenever track's mode changes.
+  if (mTrackElement) {
+    mTrackElement->MaybeDispatchLoadResource();
+  }
   // Ensure the TimeMarchesOn is called in case that the mCueList
   // is empty.
   NotifyCueUpdated(nullptr);
@@ -170,6 +195,14 @@ void TextTrack::RemoveCue(TextTrackCue& aCue, ErrorResult& aRv) {
   }
 }
 
+void TextTrack::ClearAllCues() {
+  WEBVTT_LOG("ClearAllCues");
+  ErrorResult dummy;
+  while (!mCueList->IsEmpty()) {
+    RemoveCue(*(*mCueList)[0], dummy);
+  }
+}
+
 void TextTrack::SetCuesDirty() {
   for (uint32_t i = 0; i < mCueList->Length(); i++) {
     ((*mCueList)[i])->Reset();
diff --git a/dom/media/TextTrack.h b/dom/media/TextTrack.h
index 4835e66945..dffcc5e356 100644
--- a/dom/media/TextTrack.h
+++ b/dom/media/TextTrack.h
@@ -112,6 +112,8 @@ class TextTrack final : public DOMEventTargetHelper {
                                   RefPtr<TextTrackCueList>& aOtherCues,
                                   const media::TimeInterval& aInterval) const;
 
+  void ClearAllCues();
+
  private:
   ~TextTrack();
 
diff --git a/dom/media/WebVTTListener.cpp b/dom/media/WebVTTListener.cpp
index 8733a28771..f3b6596164 100644
--- a/dom/media/WebVTTListener.cpp
+++ b/dom/media/WebVTTListener.cpp
@@ -12,6 +12,13 @@
 #include "nsIAsyncVerifyRedirectCallback.h"
 #include "nsIInputStream.h"
 
+extern mozilla::LazyLogModule gTextTrackLog;
+#define LOG(msg, ...)                     \
+  MOZ_LOG(gTextTrackLog, LogLevel::Debug, \
+          ("WebVTTListener=%p, " msg, this, ##__VA_ARGS__))
+#define LOG_WIHTOUT_ADDRESS(msg, ...) \
+  MOZ_LOG(gTextTrackLog, LogLevel::Debug, (msg, ##__VA_ARGS__))
+
 namespace mozilla {
 namespace dom {
 
@@ -28,13 +35,10 @@ NS_INTERFACE_MAP_END
 NS_IMPL_CYCLE_COLLECTING_ADDREF(WebVTTListener)
 NS_IMPL_CYCLE_COLLECTING_RELEASE(WebVTTListener)
 
-LazyLogModule gTextTrackLog("TextTrack");
-#define VTT_LOG(...) MOZ_LOG(gTextTrackLog, LogLevel::Debug, (__VA_ARGS__))
-
 WebVTTListener::WebVTTListener(HTMLTrackElement* aElement)
     : mElement(aElement), mParserWrapperError(NS_OK) {
   MOZ_ASSERT(mElement, "Must pass an element to the callback");
-  VTT_LOG("WebVTTListener created.");
+  LOG("Created listener for track element %p", aElement);
   MOZ_DIAGNOSTIC_ASSERT(
       CycleCollectedJSContext::Get() &&
       !CycleCollectedJSContext::Get()->IsInStableOrMetaStableState());
@@ -49,7 +53,7 @@ WebVTTListener::WebVTTListener(HTMLTrackElement* aElement)
   }
 }
 
-WebVTTListener::~WebVTTListener() { VTT_LOG("WebVTTListener destroyed."); }
+WebVTTListener::~WebVTTListener() { LOG("destroyed."); }
 
 NS_IMETHODIMP
 WebVTTListener::GetInterface(const nsIID& aIID, void** aResult) {
@@ -57,6 +61,9 @@ WebVTTListener::GetInterface(const nsIID& aIID, void** aResult) {
 }
 
 nsresult WebVTTListener::LoadResource() {
+  if (IsCanceled()) {
+    return NS_OK;
+  }
   // Exit if we failed to create the WebVTTParserWrapper (vtt.jsm)
   NS_ENSURE_SUCCESS(mParserWrapperError, mParserWrapperError);
 
@@ -68,6 +75,9 @@ NS_IMETHODIMP
 WebVTTListener::AsyncOnChannelRedirect(nsIChannel* aOldChannel,
                                        nsIChannel* aNewChannel, uint32_t aFlags,
                                        nsIAsyncVerifyRedirectCallback* cb) {
+  if (IsCanceled()) {
+    return NS_OK;
+  }
   if (mElement) {
     mElement->OnChannelRedirect(aOldChannel, aNewChannel, aFlags);
   }
@@ -77,14 +87,23 @@ WebVTTListener::AsyncOnChannelRedirect(nsIChannel* aOldChannel,
 
 NS_IMETHODIMP
 WebVTTListener::OnStartRequest(nsIRequest* aRequest) {
-  VTT_LOG("WebVTTListener::OnStartRequest\n");
+  if (IsCanceled()) {
+    return NS_OK;
+  }
+
+  LOG("OnStartRequest");
   return NS_OK;
 }
 
 NS_IMETHODIMP
 WebVTTListener::OnStopRequest(nsIRequest* aRequest, nsresult aStatus) {
-  VTT_LOG("WebVTTListener::OnStopRequest\n");
+  if (IsCanceled()) {
+    return NS_OK;
+  }
+
+  LOG("OnStopRequest");
   if (NS_FAILED(aStatus)) {
+    LOG("Got error status");
     mElement->SetReadyState(TextTrackReadyState::FailedToLoad);
   }
   // Attempt to parse any final data the parser might still have.
@@ -93,7 +112,7 @@ WebVTTListener::OnStopRequest(nsIRequest* aRequest, nsresult aStatus) {
     mElement->SetReadyState(TextTrackReadyState::Loaded);
   }
 
-  mElement->DropChannel();
+  mElement->CancelChannelAndListener();
 
   return aStatus;
 }
@@ -104,9 +123,12 @@ nsresult WebVTTListener::ParseChunk(nsIInputStream* aInStream, void* aClosure,
                                     uint32_t* aWriteCount) {
   nsCString buffer(aFromSegment, aCount);
   WebVTTListener* listener = static_cast<WebVTTListener*>(aClosure);
+  MOZ_ASSERT(!listener->IsCanceled());
 
   if (NS_FAILED(listener->mParserWrapper->Parse(buffer))) {
-    VTT_LOG("Unable to parse chunk of WEBVTT text. Aborting.");
+    LOG_WIHTOUT_ADDRESS(
+        "WebVTTListener=%p, Unable to parse chunk of WEBVTT text. Aborting.",
+        listener);
     *aWriteCount = 0;
     return NS_ERROR_FAILURE;
   }
@@ -118,7 +140,11 @@ nsresult WebVTTListener::ParseChunk(nsIInputStream* aInStream, void* aClosure,
 NS_IMETHODIMP
 WebVTTListener::OnDataAvailable(nsIRequest* aRequest, nsIInputStream* aStream,
                                 uint64_t aOffset, uint32_t aCount) {
-  VTT_LOG("WebVTTListener::OnDataAvailable\n");
+  if (IsCanceled()) {
+    return NS_OK;
+  }
+
+  LOG("OnDataAvailable");
   uint32_t count = aCount;
   while (count > 0) {
     uint32_t read;
@@ -135,6 +161,7 @@ WebVTTListener::OnDataAvailable(nsIRequest* aRequest, nsIInputStream* aStream,
 
 NS_IMETHODIMP
 WebVTTListener::OnCue(JS::Handle<JS::Value> aCue, JSContext* aCx) {
+  MOZ_ASSERT(!IsCanceled());
   if (!aCue.isObject()) {
     return NS_ERROR_FAILURE;
   }
@@ -152,19 +179,33 @@ WebVTTListener::OnCue(JS::Handle<JS::Value> aCue, JSContext* aCx) {
 
 NS_IMETHODIMP
 WebVTTListener::OnRegion(JS::Handle<JS::Value> aRegion, JSContext* aCx) {
+  MOZ_ASSERT(!IsCanceled());
   // Nothing for this callback to do.
   return NS_OK;
 }
 
 NS_IMETHODIMP
 WebVTTListener::OnParsingError(int32_t errorCode, JSContext* cx) {
+  MOZ_ASSERT(!IsCanceled());
   // We only care about files that have a bad WebVTT file signature right now
   // as that means the file failed to load.
   if (errorCode == ErrorCodes::BadSignature) {
+    LOG("parsing error");
     mElement->SetReadyState(TextTrackReadyState::FailedToLoad);
   }
   return NS_OK;
 }
 
+bool WebVTTListener::IsCanceled() const { return mCancel; }
+
+void WebVTTListener::Cancel() {
+  MOZ_ASSERT(!IsCanceled(), "Do not cancel canceled listener again!");
+  LOG("Cancel listen to channel's response.");
+  mCancel = true;
+  mParserWrapper->Cancel();
+  mParserWrapper = nullptr;
+  mElement = nullptr;
+}
+
 }  // namespace dom
 }  // namespace mozilla
diff --git a/dom/media/WebVTTListener.h b/dom/media/WebVTTListener.h
index 295b99f350..e35a883de8 100644
--- a/dom/media/WebVTTListener.h
+++ b/dom/media/WebVTTListener.h
@@ -41,6 +41,14 @@ class WebVTTListener final : public nsIWebVTTListener,
    */
   nsresult LoadResource();
 
+  /**
+   * When this listener is not going to be used anymore, its owner should take
+   * a responsibility to call `Cancel()` to prevent this listener making any
+   * changes for the track element.
+   */
+  bool IsCanceled() const;
+  void Cancel();
+
  private:
   ~WebVTTListener();
 
@@ -53,6 +61,7 @@ class WebVTTListener final : public nsIWebVTTListener,
   RefPtr<HTMLTrackElement> mElement;
   nsCOMPtr<nsIWebVTTParserWrapper> mParserWrapper;
   nsresult mParserWrapperError;
+  bool mCancel = false;
 };
 
 }  // namespace dom
diff --git a/dom/media/gmp/GMPServiceParent.cpp b/dom/media/gmp/GMPServiceParent.cpp
index e2552eb32d..0fe485ecca 100644
--- a/dom/media/gmp/GMPServiceParent.cpp
+++ b/dom/media/gmp/GMPServiceParent.cpp
@@ -428,7 +428,7 @@ void GeckoMediaPluginServiceParent::UnloadPlugins() {
     MutexAutoLock lock(mMutex);
     // Move all plugins references to a local array. This way mMutex won't be
     // locked when calling CloseActive (to avoid inter-locking).
-    Swap(plugins, mPlugins);
+    std::swap(plugins, mPlugins);
 
     for (GMPServiceParent* parent : mServiceParents) {
       Unused << parent->SendBeginShutdown();
diff --git a/dom/media/test/test_bug883173.html b/dom/media/test/test_bug883173.html
index 67c0f3d919..6e95f4e3ca 100644
--- a/dom/media/test/test_bug883173.html
+++ b/dom/media/test/test_bug883173.html
@@ -1,59 +1,39 @@
 <!DOCTYPE HTML>
 <html>
-<!--
-https://bugzilla.mozilla.org/show_bug.cgi?id=883173
--->
 <head>
-  <meta charset='utf-8'>
   <title>Test for Bug 883173 - TextTrackCue(List) Sorting</title>
-  <script type="text/javascript" src="/MochiKit/MochiKit.js"></script>
   <script src="/tests/SimpleTest/SimpleTest.js"></script>
   <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
 </head>
 <body>
-<p id="display"></p>
-<div id="content">
-</div>
-<pre id="test">
-<script class="testbody" type="text/javascript">
-SimpleTest.waitForExplicitFinish();
-
-var video = document.createElement("video");
-video.src = "seek.webm";
-video.preload = "metadata";
-
-var trackElement = document.createElement("track");
-trackElement.src = "bug883173.vtt";
-trackElement.kind = "subtitles";
-
-document.getElementById("content").appendChild(video);
-video.appendChild(trackElement);
-video.addEventListener("loadedmetadata",
-  function run_tests() {
-    // Re-queue run_tests() at the end of the event loop until the track
-    // element has loaded its data.
-    if (trackElement.readyState == 1) {
-      setTimeout(run_tests, 0);
-      return;
-    }
-    is(trackElement.readyState, 2, "Track::ReadyState should be set to LOADED.");
+<video id="v" src="seek.webm" preload="metadata">
+  <track src="bug883173.vtt" kind="subtitles" id="default" default>
+</video>
+<script type="text/javascript">
+/**
+ * This test is used to ensure that the cues in the cue list should be sorted by
+ * cues' start time and end time, not the present order in the file.
+ */
+function runTest() {
+  let trackElement = document.getElementById("default");
+  is(trackElement.readyState, 2, "Track::ReadyState should be set to LOADED.");
 
-    // Set mode to hidden so that the active cue lists are being updated.
-    trackElement.track.mode = "hidden";
+  let expected = [[1, 3], [1, 2], [2, 4], [2, 3], [3, 4]];
+  let cueList = trackElement.track.cues;
+  is(cueList.length, expected.length, "Cue list length should be 5.");
 
-    var expected = [[1, 3], [1, 2], [2, 4], [2, 3], [3, 4]];
-    var cueList = trackElement.track.cues;
-    is(cueList.length, expected.length, "Cue list length should be 5.");
+  for (let i = 0; i < expected.length; i++) {
+    is(cueList[i].startTime, expected[i][0],
+       `Cue's start time should be ${expected[i][0]}`);
+    is(cueList[i].endTime, expected[i][1],
+       `Cue's end time should be ${expected[i][1]}`);
+  }
 
-    for (var i = 0; i < expected.length; i++) {
-      is(cueList[i].startTime, expected[i][0], "Cue's start time should be " + expected[i][0]);
-      is(cueList[i].endTime, expected[i][1], "Cue's end time should be " + expected[i][1]);
-    }
+  SimpleTest.finish();
+}
 
-    SimpleTest.finish();
-  }
-);
+SimpleTest.waitForExplicitFinish();
+onload = runTest;
 </script>
-</pre>
 </body>
-</html>
\ No newline at end of file
+</html>
diff --git a/dom/media/test/test_bug895091.html b/dom/media/test/test_bug895091.html
index 2fa777e2df..6fa2629283 100644
--- a/dom/media/test/test_bug895091.html
+++ b/dom/media/test/test_bug895091.html
@@ -1,60 +1,60 @@
 <!DOCTYPE HTML>
 <html>
-<!--
-https://bugzilla.mozilla.org/show_bug.cgi?id=895091
--->
 <head>
-  <meta charset='utf-8'>
   <title>Test for Bug 895091 - Integrating vtt.js</title>
-  <script type="text/javascript" src="/MochiKit/MochiKit.js"></script>
   <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="manifest.js"></script>
   <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
 </head>
 <body>
-<p id="display"></p>
-<div id="content">
-</div>
-<pre id="test">
-<script class="testbody" type="text/javascript">
-SimpleTest.waitForExplicitFinish();
-
-var video = document.createElement("video");
-video.src = "seek.webm";
-video.preload = "metadata";
-
-var trackElement = document.createElement("track");
-trackElement.src = "long.vtt";
-trackElement.kind = "subtitles";
-
-var trackElementTwo = document.createElement("track");
-trackElementTwo.src = "long.vtt";
-trackElementTwo.kind = "subtitles";
-
-document.getElementById("content").appendChild(video);
-video.appendChild(trackElement);
-video.appendChild(trackElementTwo);
-
-video.addEventListener("loadedmetadata", function run_tests() {
-  // Re-que run_tests() at the end of the event loop until the track
-  // element has loaded its data.
-  if (trackElement.readyState == 1 || trackElementTwo.readyState == 1) {
-    setTimeout(run_tests, 0);
-    return;
-  }
+<video id="v" src="seek.webm" preload="metadata">
+  <track src="long.vtt" kind="subtitles" id="track1">
+  <track src="long.vtt" kind="subtitles" id="track2">
+</video>
+<script type="text/javascript">
+/**
+ * This test is used to ensure that we can load two track elements with large
+ * amount of cues at same time. In this test, both tracks are disable by default,
+ * we have to enable them in order to start loading.
+ */
+var trackElement = document.getElementById("track1");
+var trackElementTwo = document.getElementById("track2");
+
+async function runTest() {
+  enableBothTracks();
+  await waitUntilBothTracksLoaded();
+  checkTrackReadyStateShouldBeLoaded();
+  checkCuesAmount();
+  SimpleTest.finish();
+}
 
-  // Set mode to hidden so that the active cue lists are being updated.
+SimpleTest.waitForExplicitFinish();
+onload = runTest;
+
+/**
+ * The following are test helper functions.
+ */
+function enableBothTracks() {
+  // All tracks are `disable` on default. As we won't start loading for disabled
+  // tracks, we have to change their mode in order to start loading.
   trackElement.track.mode = "hidden";
   trackElementTwo.track.mode = "hidden";
+}
+
+async function waitUntilBothTracksLoaded() {
+  info(`wait until both tracks finish loading`);
+  await Promise.all([once(trackElement, "load"), once(trackElementTwo, "load")]);
+}
 
+function checkTrackReadyStateShouldBeLoaded() {
   is(trackElement.readyState, 2, "Track::ReadyState should be set to LOADED.");
   is(trackElementTwo.readyState, 2, "Track::ReadyState should be set to LOADED.");
+}
 
+function checkCuesAmount() {
   is(trackElement.track.cues.length, 2000, "Cue list length should be 2000.");
   is(trackElementTwo.track.cues.length, 2000, "Cue list length should be 2000.");
-
-  SimpleTest.finish();
-});
+}
 </script>
-</pre>
 </body>
 </html>
diff --git a/dom/media/test/test_texttrack.html b/dom/media/test/test_texttrack.html
index 2c413d02f8..69c4f24bec 100644
--- a/dom/media/test/test_texttrack.html
+++ b/dom/media/test/test_texttrack.html
@@ -1,126 +1,158 @@
 <!DOCTYPE HTML>
 <html>
-<!--
-https://bugzilla.mozilla.org/show_bug.cgi?id=833386
--->
 <head>
-  <meta charset='utf-8'>
   <title>Test for Bug 833386 - TextTrackList</title>
-  <script type="text/javascript" src="/MochiKit/MochiKit.js"></script>
   <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="manifest.js"></script>
   <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
 </head>
 <body>
-<p id="display"></p>
-<div id="content" style="display: none">
-</div>
-<pre id="test">
-<script class="testbody" type="text/javascript">
-SimpleTest.waitForExplicitFinish();
-SpecialPowers.pushPrefEnv({"set": [["media.webvtt.regions.enabled", true]]},
-  function() {
-    var video = document.createElement("video");
-
-    isnot(video.textTracks, undefined, "HTMLMediaElement::TextTrack() property should be available.")
-
-    var trackList = video.textTracks;
-    is(trackList.length, 0, "Length should be 0.");
-
-    ok(typeof video.addTextTrack == "function", "HTMLMediaElement::AddTextTrack() function should be available.")
-    video.addTextTrack("subtitles", "third", "en-CA");
-    is(trackList.length, 1, "Length should be 1.");
-
-    var textTrack = video.textTracks[0];
-    is(textTrack.label, "third", "Label should be set to third.");
-    is(textTrack.language, "en-CA", "Language should be en-CA.");
-    is(textTrack.kind, "subtitles", "Default kind should be subtitles.");
-    is(textTrack.mode, "hidden", "Default mode should be hidden.");
-
-    // Mode should not allow a bogus value.
-    textTrack.mode = 'bogus';
-    is(textTrack.mode, 'hidden', "Mode should be not allow a bogus value.");
+<video id="v">
+<script type="text/javascript">
+/**
+ * This test is used to check different things.
+ * (1) the default value of track element's attributes
+ * (2) readonly attributes can't be modifted
+ * (3) the order of tracks in the media element's track list
+ */
+var enabledTrackElement = null;
+
+async function runTest() {
+  addFourTextTrackElementsToVideo();
+  startLoadingVideo();
+  await waitUntilEnableTrackLoaded();
+  checkTracksStatus();
+  SimpleTest.finish();
+}
 
-    // Should allow all these values for mode.
-    checkMode("showing", "Mode should allow \"showing\"");
-    checkMode("disabled", "Mode should allow \"disabled\"");
-    checkMode("hidden", "Mode should allow \"hidden\"");
-
-    // All below are read-only properties and so should not allow setting.
-    textTrack.label = "French subtitles";
-    is(textTrack.label, "third", "Label is read-only so should still be \"label\".");
-
-    textTrack.language = "en";
-    is(textTrack.language, "en-CA", "Language is read-only so should still be \"en-CA\".");
-
-    textTrack.kind = "captions";
-    is(textTrack.kind, "subtitles", "Kind is read-only so should still be \"subtitles\"");
-
-    function checkMode(value, message) {
-      textTrack.mode = value;
-      is(textTrack.mode, value, message);
+SimpleTest.waitForExplicitFinish();
+onload = runTest;
+
+/**
+ * The following are test helper functions.
+ */
+function addFourTextTrackElementsToVideo() {
+  let video = document.getElementById("v");
+  isnot(video.textTracks, undefined,
+        "HTMLMediaElement::TextTrack() property should be available.")
+
+  let trackList = video.textTracks;
+  is(trackList.length, 0, "Length should be 0.");
+
+  ok(typeof video.addTextTrack == "function",
+     "HTMLMediaElement::AddTextTrack() function should be available.")
+
+  // Insert some tracks in an order that is not sorted, we will test if they
+  // are sorted later.
+  info(`- Add a track element with label 'third' -`);
+  video.addTextTrack("subtitles", "third", "en-CA");
+  is(trackList.length, 1, "Length should be 1.");
+
+  let textTrack = video.textTracks[0];
+  checkAttributesDefaultValue(textTrack);
+  checkTextTrackMode(textTrack);
+  checkReadOnlyAttributes(textTrack);
+
+  info(`- Add a track element with label 'first' -`);
+  let trackOne = document.createElement("track");
+  video.appendChild(trackOne);
+  trackOne.label = "first";
+  trackOne.src = "basic.vtt";
+  trackOne.default = true;
+  trackOne.id = "2";
+  // The automatic track selection would choose the first track element with
+  // `default` attribute, so this track would be enable later.
+  enabledTrackElement = trackOne;
+
+  info(`- Add a track element with label 'fourth' -`);
+  video.addTextTrack("subtitles", "fourth", "en-CA");
+
+  info(`- Add a track element with label 'second' -`);
+  let trackTwo = document.createElement("track");
+  video.appendChild(trackTwo);
+  trackTwo.label = "second";
+  trackTwo.src = "basic.vtt";
+  // Although this track has `default` attribute as well, it won't be enable by
+  // the automatic track selection because it's not the first default track in
+  // the media element's track list.
+  trackTwo.default = true;
+}
+
+function checkAttributesDefaultValue(track) {
+  is(track.label, "third", "Label should be set to third.");
+  is(track.language, "en-CA", "Language should be en-CA.");
+  is(track.kind, "subtitles", "Default kind should be subtitles.");
+  is(track.mode, "hidden", "Default mode should be hidden.");
+}
+
+function checkTextTrackMode(track) {
+  // Mode should not allow a bogus value.
+  track.mode = 'bogus';
+  is(track.mode, 'hidden', "Mode should be not allow a bogus value.");
+
+  // Should allow all these values for mode.
+  changeTextTrackMode("showing");
+  changeTextTrackMode("disabled");
+  changeTextTrackMode("hidden");
+
+  function changeTextTrackMode(mode) {
+    track.mode = mode;
+    is(track.mode, mode, `Mode should allow \"${mode}\"`);
+  }
+}
+
+function checkReadOnlyAttributes(track) {
+  // All below are read-only properties and so should not allow setting.
+  track.label = "French subtitles";
+  is(track.label, "third", "Label is read-only so should still be \"label\".");
+  track.language = "en";
+  is(track.language, "en-CA", "Language is read-only so should still be \"en-CA\".");
+  track.kind = "captions";
+  is(track.kind, "subtitles", "Kind is read-only so should still be \"subtitles\"");
+}
+
+function startLoadingVideo() {
+  let video = document.getElementById("v");
+  video.src = "seek.webm";
+  video.preload = "metadata";
+}
+
+async function waitUntilEnableTrackLoaded() {
+  info(`wait until the enabled track finishes loading`);
+  await once(enabledTrackElement, "load");
+  is(enabledTrackElement.readyState, 2, "Track::ReadyState should be set to LOADED.");
+}
+
+function checkTracksStatus() {
+  // We're testing two things here,
+  // (1) the tracks created from a track element have a default mode 'disabled'
+  // and tracks created from 'addTextTrack' method have a default
+  // mode of 'hidden'.
+  // (2) we're testing that the tracks are sorted properly. For the tracks to
+  // be sorted the first two tracks, added through a TrackElement, must occupy
+  // the first two indexes in their TrackElement tree order. The second two
+  // tracks, added through the 'addTextTrack' method, will occupy the last two
+  // indexes in the order that they were added in.
+  let trackData = [
+    { label: "first", mode: "showing", id: "2" },
+    { label: "second", mode: "disabled", id: "" },
+    { label: "third", mode: "hidden", id: "" },
+    { label: "fourth", mode: "hidden", id: "" }
+  ];
+  let video = document.getElementById("v");
+  is(video.textTracks.length, trackData.length,
+     `TextTracks length should be ${trackData.length}`);
+  for (let i = 0; i < trackData.length; i++) {
+    let track = video.textTracks[i];
+    isnot(track, null, `Video should have a text track at index ${i}`);
+    let info = trackData[i];
+    for (let key in info) {
+      is(track[key], info[key],
+         `Track at index ${i} should have a '${key}' property with a value of '${info[key]}'.`);
     }
+  }
+}
 
-    // Insert some tracks in an order that is not sorted, we will test if they
-    // are sorted later.
-    var trackOne = document.createElement("track");
-    trackOne.label = "first";
-    trackOne.src = "basic.vtt";
-    trackOne.default = true;
-    trackOne.id = "2";
-    video.appendChild(trackOne);
-
-    video.addTextTrack("subtitles", "fourth", "en-CA");
-
-    var trackTwo = document.createElement("track");
-    trackTwo.label = "second";
-    trackTwo.src = "basic.vtt";
-    trackTwo.default = true;
-    video.appendChild(trackTwo);
-
-    video.src = "seek.webm";
-    video.preload = "metadata";
-
-    document.getElementById("content").appendChild(video);
-
-    video.addEventListener("loadedmetadata", function run_tests() {
-      // Re-que run_tests() at the end of the event loop until the track
-      // element has loaded its data.
-      if (trackOne.readyState == 1 || trackTwo.readyState == 1) {
-        setTimeout(run_tests, 0);
-        return;
-      }
-      is(trackOne.readyState, 2, "First Track::ReadyState should be set to LOADED.");
-      is(trackTwo.readyState, 2, "Second Track::ReadyState should be set to LOADED.");
-
-      // We're testing two things here, firstly that tracks created from a track
-      // element have a default mode 'disabled' and tracks created with the
-      // 'addTextTrack' method have a default mode of 'hidden'.
-      // Secondly we're testing that the tracks are sorted properly.
-      // For the tracks to be sorted the first two tracks, added through a
-      // TrackElement, must occupy the first two indexes in their TrackElement
-      // tree order. The second two tracks, added through the 'addTextTrack'
-      // method, will occupy the last two indexes in the order that they were
-      // added in.
-      var trackData = [
-        { label: "first", mode: "showing", id: "2" },
-        { label: "second", mode: "disabled", id: "" },
-        { label: "third", mode: "hidden", id: "" },
-        { label: "fourth", mode: "hidden", id: "" }
-      ];
-      is(video.textTracks.length, trackData.length, "TextTracks length should be " + trackData.length);
-      for (var i = 0; i < trackData.length; i++) {
-        var track = video.textTracks[i];
-        isnot(track, null, "Video should have a text track at index " + i);
-        var info = trackData[i];
-        for (var key in info) {
-          is(track[key], info[key], "Track at index " + i + " should have a '" + key + "'' property " +
-                                    "with a value of '" + info[key] + "'.");
-        }
-      }
-      SimpleTest.finish();
-    });
-});
 </script>
-</pre>
 </body>
 </html>
diff --git a/dom/media/test/test_texttrack_moz.html b/dom/media/test/test_texttrack_moz.html
index 515b36804b..b39562b3a4 100644
--- a/dom/media/test/test_texttrack_moz.html
+++ b/dom/media/test/test_texttrack_moz.html
@@ -1,66 +1,60 @@
 <!DOCTYPE HTML>
 <html>
-<!--
-https://bugzilla.mozilla.org/show_bug.cgi?id=881976
--->
 <head>
-  <meta charset='utf-8'>
-  <title>Test for Bug 881976 - TextTrackCue Computed Position</title>
-  <script type="text/javascript" src="/MochiKit/MochiKit.js"></script>
+  <title>Test for Bug 881976 - TextTrackList</title>
   <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="manifest.js"></script>
   <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
 </head>
 <body>
-<p id="display"></p>
-<div id="content">
-</div>
-<pre id="test">
-<script class="testbody" type="text/javascript">
-  SimpleTest.waitForExplicitFinish();
-  SpecialPowers.pushPrefEnv({"set": [["media.webvtt.regions.enabled", true]]},
-    function() {
-      var video = document.createElement("video");
+<video id="v" src="seek.webm" preload="metadata">
+<script type="text/javascript">
+/**
+ * This test is used to ensure the text track list we got from video is as same
+ * as the one in the text track.
+ */
+var video = document.getElementById("v");
+
+async function runTest() {
+  addTrackViaAddTrackAPI();
+  await addTrackViaTrackElement();
+  SimpleTest.finish();
+}
+
+SimpleTest.waitForExplicitFinish();
+onload = runTest;
+
+/**
+ * The following are test helper functions.
+ */
+function addTrackViaAddTrackAPI() {
+  // Check if adding a text track manually sets the TextTrackList correctly.
+  video.addTextTrack("subtitles", "", "");
+  // TextTrack.textTrackList is an extension available only to privileged code,
+  // so we need to access it through the SpecialPowers object.
+  is(SpecialPowers.unwrap(SpecialPowers.wrap(video.textTracks[0]).textTrackList),
+     video.textTracks,
+     "The Track's TextTrackList should be the Video's TextTrackList.");
+}
+
+async function addTrackViaTrackElement() {
+  // Check if loading a Track via a TrackElement sets the TextTrackList correctly.
+  let trackElement = document.createElement("track");
+  trackElement.src = "basic.vtt";
+  trackElement.kind = "subtitles";
+  trackElement.default = true;
+  video.appendChild(trackElement);
+
+  info(`wait until the track finishes loading`);
+  await once(trackElement, "load");
+
+  is(trackElement.readyState, HTMLTrackElement.LOADED,
+     "Track::ReadyState should be set to LOADED.");
+  is(SpecialPowers.unwrap(SpecialPowers.wrap(trackElement.track).textTrackList),
+     video.textTracks,
+     "TrackElement's Track's TextTrackList should be the Video's TextTrackList.");
+}
 
-      // Check if adding a text track manually sets the TextTrackList correctly.
-
-      // HTMLTrackElement.textTrackList is an extension available only to
-      // privileged code, so we need to access it through the SpecialPowers
-      // object.
-      video.addTextTrack("subtitles", "", "");
-      is(SpecialPowers.unwrap(SpecialPowers.wrap(video.textTracks[0]).textTrackList),
-          video.textTracks,
-          "The Track's TextTrackList should be the Video's TextTrackList.");
-
-
-      // Check if loading a Track via a TrackElement sets the TextTrackList correctly.
-      video.src = "seek.webm";
-      video.preload = "auto";
-
-      var trackElement = document.createElement("track");
-      trackElement.src = "basic.vtt";
-      trackElement.kind = "subtitles";
-
-      video.appendChild(trackElement);
-      document.getElementById("content").appendChild(video);
-
-      video.addEventListener("loadedmetadata", function run_tests() {
-        // Re-que run_tests() at the end of the event loop until the track
-        // element has loaded its data.
-        if (trackElement.readyState == HTMLTrackElement.LOADING) {
-          setTimeout(run_tests, 0);
-          return;
-        }
-        is(trackElement.readyState, HTMLTrackElement.LOADED,
-            "Track::ReadyState should be set to LOADED.");
-        is(SpecialPowers.unwrap(SpecialPowers.wrap(trackElement.track).textTrackList),
-           video.textTracks,
-           "TrackElement's Track's TextTrackList should be the Video's TextTrackList.");
-
-        SimpleTest.finish();
-      });
-    }
-  );
 </script>
-</pre>
 </body>
 </html>
diff --git a/dom/media/test/test_texttrackcue.html b/dom/media/test/test_texttrackcue.html
index 112e3e09c3..92bb327b63 100644
--- a/dom/media/test/test_texttrackcue.html
+++ b/dom/media/test/test_texttrackcue.html
@@ -1,268 +1,299 @@
 <!DOCTYPE HTML>
 <html>
-<!--
-https://bugzilla.mozilla.org/show_bug.cgi?id=833386
--->
 <head>
-  <meta charset='utf-8'>
   <title>Test for Bug 833386 - HTMLTrackElement</title>
-  <script type="text/javascript" src="/MochiKit/MochiKit.js"></script>
   <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="manifest.js"></script>
   <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
 </head>
 <body>
-<p id="display"></p>
-<div id="content">
-</div>
-<pre id="test">
-<script class="testbody" type="text/javascript">
+<video id="v" src="seek.webm" preload="metadata">
+  <track src="basic.vtt" kind="subtitles" id="default" default>
+</video>
+<script type="text/javascript">
+/**
+ * This test is used to test the VTTCue's different behaviors and check whether
+ * cues would be activatived correctly during video playback.
+ */
+var video = document.getElementById("v");
+var trackElement = document.getElementById("default");
+
+async function runTest() {
+  await waitUntiTrackLoaded();
+  checkCueDefinition();
+  checkFirstCueParsedContent();
+  checkCueStartTimeAndEndtime();
+  checkCueSizeAndPosition();
+  checkCueSnapToLines();
+  checkCueAlignmentAndWritingDirection();
+  checkCueLine();
+  checkCreatingNewCue();
+  checkRemoveNonExistCue();
+  checkActiveCues();
+  checkCueRegion();
+  await checkCActiveCuesDuringVideoPlaying();
+  SimpleTest.finish();
+}
+
 SimpleTest.waitForExplicitFinish();
 SpecialPowers.pushPrefEnv({"set": [["media.webvtt.regions.enabled", true]]},
-  function() {
-    var video = document.createElement("video");
-    video.src = "seek.webm";
-    video.preload = "metadata";
-
-    var trackElement = document.createElement("track");
-    trackElement.src = "basic.vtt";
-    trackElement.kind = "subtitles";
-
-    document.getElementById("content").appendChild(video);
-    video.appendChild(trackElement);
-    video.addEventListener("loadedmetadata", function run_tests() {
-      // Re-que run_tests() at the end of the event loop until the track
-      // element has loaded its data.
-      if (trackElement.readyState == 1) {
-        setTimeout(run_tests, 0);
-        return;
-      }
-
-      is(trackElement.readyState, 2, "Track::ReadyState should be set to LOADED.");
-      // Set mode to hidden so that the active cue lists are being updated.
-      trackElement.track.mode = "hidden";
-
-      var cueList = trackElement.track.cues;
-      is(cueList.length, 6, "Cue list length should be 6.");
-
-      // Check that the typedef of TextTrackCue works in Gecko.
-      isnot(window.TextTrackCue, undefined, "TextTrackCue should be defined.");
-      isnot(window.VTTCue, undefined, "VTTCue should be defined.");
-
-      // Check if first cue was parsed correctly.
-      var cue = cueList[0];
-      ok(cue instanceof TextTrackCue, "Cue should be an instanceof TextTrackCue.");
-      ok(cue instanceof VTTCue, "Cue should be an instanceof VTTCue.");
-      is(cue.id, "1", "Cue's ID should be 1.");
-      is(cue.startTime, 0.5, "Cue's start time should be 0.5.");
-      is(cue.endTime, 0.7, "Cue's end time should be 0.7.");
-      is(cue.pauseOnExit, false, "Cue's pause on exit flag should be false.");
-      is(cue.text, "This", "Cue's text should be set correctly.");
-      is(cue.track, trackElement.track, "Cue's track should be defined.");
-
-      cue.track = null;
-      isnot(cue.track, null, "Cue's track should not be able to be set.");
-
-      // Check that all cue times were not rounded
-      is(cueList[1].startTime, 1.2, "Second cue's start time should be 1.2.");
-      is(cueList[1].endTime, 2.4, "Second cue's end time should be 2.4.");
-      is(cueList[2].startTime, 2, "Third cue's start time should be 2.");
-      is(cueList[2].endTime, 3.5, "Third cue's end time should be 3.5.");
-      is(cueList[3].startTime, 2.71, "Fourth cue's start time should be 2.71.");
-      is(cueList[3].endTime, 2.91, "Fourth cue's end time should be 2.91.");
-      is(cueList[4].startTime, 3.217, "Fifth cue's start time should be 3.217.");
-      is(cueList[4].endTime, 3.989, "Fifth cue's end time should be 3.989.");
-      is(cueList[5].startTime, 3.217, "Sixth cue's start time should be 3.217.");
-      is(cueList[5].endTime, 3.989, "Sixth cue's end time should be 3.989.");
-
-      // Check that Cue setters are working correctly.
-      cue.id = "Cue 01";
-      is(cue.id, "Cue 01", "Cue's ID should be 'Cue 01'.");
-      cue.startTime = 0.51;
-      is(cue.startTime, 0.51, "Cue's start time should be 0.51.");
-      cue.endTime = 0.71;
-      is(cue.endTime, 0.71, "Cue's end time should be 0.71.");
-      cue.pauseOnExit = true;
-      is(cue.pauseOnExit, true, "Cue's pause on exit flag should be true.");
-      video.addEventListener("pause", function() {
-        video.play();
-      }, {once: true});
-
-      var exceptionHappened;
-      function checkPercentageValue(prop, initialVal) {
-        ok(prop in cue, prop + " should be a property on VTTCue.");
-        cue[prop] = initialVal;
-        is(cue[prop], initialVal, "Cue's " + prop + " should initially be " + initialVal);
-        [ 101, -1 ].forEach(function(val) {
-          exceptionHappened = false;
-          try {
-            cue[prop] = val;
-          } catch(e) {
-            exceptionHappened = true;
-            is(e.name, "IndexSizeError", "Should have thrown IndexSizeError.");
-          }
-          ok(exceptionHappened, "Exception should have happened.");
-        });
-      }
-
-      checkPercentageValue("size", 100.0);
-      cue.size = 50.5;
-      is(cue.size, 50.5, "Cue's size should be 50.5.")
-
-      // Check cue.position
-      checkPercentageValue("position", "auto");
-      cue.position = 50.5;
-      is(cue.position, 50.5, "Cue's position value should now be 50.5.");
-
-      ok(cue.snapToLines, "Cue's snapToLines should be set by set.");
-      cue.snapToLines = false;
-      ok(!cue.snapToLines, "Cue's snapToLines should not be set.");
-
-      function checkEnumValue(prop, initialVal, acceptedValues) {
-        ok(prop in cue, prop + " should be a property on VTTCue.");
-        is(cue[prop], initialVal, "Cue's " + prop + " should be " + initialVal);
-        cue[prop] = "bogus";
-        is(cue[prop], initialVal, "Cue's " + prop + " should be " + initialVal);
-        acceptedValues.forEach(function(val) {
-          cue[prop] = val;
-          is(cue[prop], val, "Cue's " + prop + " should be " + val);
-          if (typeof val === "string") {
-            cue[prop] = val.toUpperCase();
-            is(cue[prop], val, "Cue's " + prop + " should be " + val);
-          }
-        });
-      }
-
-      checkEnumValue("align", "center", [ "start", "left", "center", "right", "end" ]);
-      checkEnumValue("lineAlign", "start", [ "start", "center", "end" ]);
-      checkEnumValue("vertical", "", [ "", "lr", "rl" ]);
-
-      cue.lineAlign = "center";
-      is(cue.lineAlign, "center", "Cue's line align should be center.");
-      cue.lineAlign = "START";
-      is(cue.lineAlign, "center", "Cue's line align should be center.");
-      cue.lineAlign = "end";
-      is(cue.lineAlign, "end", "Cue's line align should be end.");
-
-      // Check that cue position align works properly
-      is(cue.positionAlign, "auto", "Cue's default position alignment should be auto.");
-
-      cue.positionAlign = "line-left";
-      is(cue.positionAlign, "line-left", "Cue's position align should be line-left.");
-      cue.positionAlign = "auto";
-      is(cue.positionAlign, "auto", "Cue's position align should be auto.");
-      cue.positionAlign = "line-right";
-      is(cue.positionAlign, "line-right", "Cue's position align should be line-right.");
-
-      // Check cue.line
-      is(cue.line, "auto", "Cue's line value should initially be auto.");
-      cue.line = 0.5;
-      is(cue.line, 0.5, "Cue's line value should now be 0.5.");
-      cue.line = "auto";
-      is(cue.line, "auto", "Cue's line value should now be auto.");
-
-      // Check that we can create and add new VTTCues
-      var vttCue = new VTTCue(3.999, 4, "foo");
-      is(vttCue.track, null, "Cue's track should be null.");
-      trackElement.track.addCue(vttCue);
-      is(cue.track, trackElement.track, "Cue's track should be defined.");
-      is(cueList.length, 7, "Cue list length should now be 7.");
-
-      // Check that new VTTCue was added correctly
-      cue = cueList[6];
-      is(cue.startTime, 3.999, "Cue's start time should be 3.999.");
-      is(cue.endTime, 4, "Cue's end time should be 4.");
-      is(cue.text, "foo", "Cue's text should be foo.");
-
-      // Adding the same cue again should not increase the cue count.
-      trackElement.track.addCue(vttCue);
-      is(cueList.length, 7, "Cue list length should be 7.");
-
-      // Check that we are able to remove cues.
-      trackElement.track.removeCue(cue);
-      is(cueList.length, 6, "Cue list length should be 6.");
-
+                            runTest);
+/**
+ * The following are test helper functions.
+ */
+async function waitUntiTrackLoaded() {
+  if (trackElement.readyState != 2) {
+    info(`wait until the track finishes loading`);
+    await once(trackElement, "load");
+  }
+  is(trackElement.readyState, 2, "Track::ReadyState should be set to LOADED.");
+  is(trackElement.track.cues.length, 6, "Cue list length should be 6.");
+}
+
+function checkCueDefinition() {
+  // Check that the typedef of TextTrackCue works in Gecko.
+  isnot(window.TextTrackCue, undefined, "TextTrackCue should be defined.");
+  isnot(window.VTTCue, undefined, "VTTCue should be defined.");
+}
+
+function checkFirstCueParsedContent() {
+  // Check if first cue was parsed correctly.
+  const cue = trackElement.track.cues[0];
+  ok(cue instanceof TextTrackCue, "Cue should be an instanceof TextTrackCue.");
+  ok(cue instanceof VTTCue, "Cue should be an instanceof VTTCue.");
+  is(cue.id, "1", "Cue's ID should be 1.");
+  is(cue.startTime, 0.5, "Cue's start time should be 0.5.");
+  is(cue.endTime, 0.7, "Cue's end time should be 0.7.");
+  is(cue.pauseOnExit, false, "Cue's pause on exit flag should be false.");
+  is(cue.text, "This", "Cue's text should be set correctly.");
+  is(cue.track, trackElement.track, "Cue's track should be defined.");
+  cue.track = null;
+  isnot(cue.track, null, "Cue's track should not be able to be set.");
+}
+
+function checkCueStartTimeAndEndtime() {
+  const cueList = trackElement.track.cues;
+  // Check that all cue times were not rounded
+  is(cueList[1].startTime, 1.2, "Second cue's start time should be 1.2.");
+  is(cueList[1].endTime, 2.4, "Second cue's end time should be 2.4.");
+  is(cueList[2].startTime, 2, "Third cue's start time should be 2.");
+  is(cueList[2].endTime, 3.5, "Third cue's end time should be 3.5.");
+  is(cueList[3].startTime, 2.71, "Fourth cue's start time should be 2.71.");
+  is(cueList[3].endTime, 2.91, "Fourth cue's end time should be 2.91.");
+  is(cueList[4].startTime, 3.217, "Fifth cue's start time should be 3.217.");
+  is(cueList[4].endTime, 3.989, "Fifth cue's end time should be 3.989.");
+  is(cueList[5].startTime, 3.217, "Sixth cue's start time should be 3.217.");
+  is(cueList[5].endTime, 3.989, "Sixth cue's end time should be 3.989.");
+
+  // Check that Cue setters are working correctly.
+  const cue = trackElement.track.cues[0];
+  cue.id = "Cue 01";
+  is(cue.id, "Cue 01", "Cue's ID should be 'Cue 01'.");
+  cue.startTime = 0.51;
+  is(cue.startTime, 0.51, "Cue's start time should be 0.51.");
+  cue.endTime = 0.71;
+  is(cue.endTime, 0.71, "Cue's end time should be 0.71.");
+  cue.pauseOnExit = true;
+  is(cue.pauseOnExit, true, "Cue's pause on exit flag should be true.");
+  video.addEventListener("pause", function() {
+    video.play();
+  }, {once: true});
+}
+
+function checkCueSizeAndPosition() {
+  function checkPercentageValue(prop, initialVal) {
+    ok(prop in cue, prop + " should be a property on VTTCue.");
+    cue[prop] = initialVal;
+    is(cue[prop], initialVal, `Cue's ${prop} should initially be ${initialVal}`);
+    [ 101, -1 ].forEach(function(val) {
       exceptionHappened = false;
       try {
-        // We should not be able to remove a cue that is not in the list.
-        cue = new VTTCue(1, 2, "foo");
-        trackElement.track.removeCue(cue);
-      } catch (e) {
-        // "NotFoundError" should be thrown when trying to remove a cue that is
-        // not in the list.
-        is(e.name, "NotFoundError", "Should have thrown NotFoundError.");
+        cue[prop] = val;
+      } catch(e) {
         exceptionHappened = true;
+        is(e.name, "IndexSizeError", "Should have thrown IndexSizeError.");
       }
-      // If this is false then we did not throw an error and probably removed a cue
-      // when we shouln't have.
       ok(exceptionHappened, "Exception should have happened.");
+    });
+  }
 
-      is(cueList.length, 6, "Cue list length should be 6.");
-
-      video.currentTime = 2;
-      isnot(trackElement.track.activeCues, null);
-
-      trackElement.track.mode = "disabled";
-      is(trackElement.track.activeCues, null);
-
-      trackElement.track.mode = "showing";
-      video.currentTime = 0;
-
-      var regionInfo = [
-        { lines: 2, width: 30 },
-        { lines: 4, width: 20 },
-        { lines: 2, width: 30 }
-      ];
-
-      for (var i = 0; i < regionInfo.length; i++) {
-        var cue = cueList[i];
-        isnot(cue.region, null, "Cue at " + i + " should have a region.");
-        for (var key in regionInfo[i]) {
-          is(cue.region[key], regionInfo[i][key], "Region should have a " + key +
-                                                  " property with a value of " + regionInfo[i][key])
-        }
+  const cue = trackElement.track.cues[0];
+  checkPercentageValue("size", 100.0);
+  cue.size = 50.5;
+  is(cue.size, 50.5, "Cue's size should be 50.5.")
+
+  // Check cue.position
+  checkPercentageValue("position", "auto");
+  cue.position = 50.5;
+  is(cue.position, 50.5, "Cue's position value should now be 50.5.");
+}
+
+function checkCueSnapToLines() {
+  const cue = trackElement.track.cues[0];
+  ok(cue.snapToLines, "Cue's snapToLines should be set by set.");
+  cue.snapToLines = false;
+  ok(!cue.snapToLines, "Cue's snapToLines should not be set.");
+}
+
+function checkCueAlignmentAndWritingDirection() {
+  function checkEnumValue(prop, initialVal, acceptedValues) {
+    ok(prop in cue, `${prop} should be a property on VTTCue.`);
+    is(cue[prop], initialVal, `Cue's ${prop} should be ${initialVal}`);
+    cue[prop] = "bogus";
+    is(cue[prop], initialVal, `Cue's ${prop} should be ${initialVal}`);
+    acceptedValues.forEach(function(val) {
+      cue[prop] = val;
+      is(cue[prop], val, `Cue's ${prop} should be ${val}`);
+      if (typeof val === "string") {
+        cue[prop] = val.toUpperCase();
+        is(cue[prop], val, `Cue's ${prop} should be ${val}`);
       }
+    });
+  }
 
-      // Test TextTrack::ActiveCues.
-      var cueInfo = [
-        { startTime: 0.51, endTime: 0.71, ids: ["Cue 01"] },
-        { startTime: 0.72, endTime: 1.19, ids: [] },
-        { startTime: 1.2, endTime: 1.9, ids: [2] },
-        { startTime: 2, endTime: 2.4, ids: [2, 2.5] },
-        { startTime: 2.41, endTime: 2.70, ids: [2.5] },
-        { startTime: 2.71, endTime: 2.91, ids: [2.5, 3] },
-        { startTime: 2.92, endTime: 3.216, ids: [2.5] },
-        { startTime: 3.217, endTime: 3.5, ids: [2.5, 4, 5] },
-        { startTime: 3.51, endTime: 3.989, ids: [4, 5] },
-        { startTime: 3.99, endTime: 4, ids: [] }
-      ];
-
-      video.addEventListener("timeupdate", function() {
-        var activeCues = trackElement.track.activeCues,
-            found = false,
-            playbackTime = video.currentTime;
-
-        for (var i = 0; i < cueInfo.length; i++) {
-          var cue = cueInfo[i];
-          if (playbackTime >= cue.startTime && playbackTime < cue.endTime) {
-            is(activeCues.length, cue.ids.length, "There should be " + cue.ids.length + " currently active cue(s).");
-            for (var j = 0; j < cue.ids.length; j++) {
-              isnot(activeCues.getCueById(cue.ids[j]), undefined, "The cue with ID " + cue.ids[j] + " should be active.");
-            }
-            break;
-          }
+  const cue = trackElement.track.cues[0];
+  checkEnumValue("align", "center", [ "start", "left", "center", "right", "end" ]);
+  checkEnumValue("lineAlign", "start", [ "start", "center", "end" ]);
+  checkEnumValue("vertical", "", [ "", "lr", "rl" ]);
+
+  cue.lineAlign = "center";
+  is(cue.lineAlign, "center", "Cue's line align should be center.");
+  cue.lineAlign = "START";
+  is(cue.lineAlign, "center", "Cue's line align should be center.");
+  cue.lineAlign = "end";
+  is(cue.lineAlign, "end", "Cue's line align should be end.");
+
+  // Check that cue position align works properly
+  is(cue.positionAlign, "auto", "Cue's default position alignment should be auto.");
+
+  cue.positionAlign = "line-left";
+  is(cue.positionAlign, "line-left", "Cue's position align should be line-left.");
+  cue.positionAlign = "auto";
+  is(cue.positionAlign, "auto", "Cue's position align should be auto.");
+  cue.positionAlign = "line-right";
+  is(cue.positionAlign, "line-right", "Cue's position align should be line-right.");
+}
+
+function checkCueLine() {
+  const cue = trackElement.track.cues[0];
+  // Check cue.line
+  is(cue.line, "auto", "Cue's line value should initially be auto.");
+  cue.line = 0.5;
+  is(cue.line, 0.5, "Cue's line value should now be 0.5.");
+  cue.line = "auto";
+  is(cue.line, "auto", "Cue's line value should now be auto.");
+}
+
+function checkCreatingNewCue() {
+  const cueList = trackElement.track.cues;
+
+  // Check that we can create and add new VTTCues
+  let vttCue = new VTTCue(3.999, 4, "foo");
+  is(vttCue.track, null, "Cue's track should be null.");
+  trackElement.track.addCue(vttCue);
+  is(vttCue.track, trackElement.track, "Cue's track should be defined.");
+  is(cueList.length, 7, "Cue list length should now be 7.");
+
+  // Check that new VTTCue was added correctly
+  let cue = cueList[6];
+  is(cue.startTime, 3.999, "Cue's start time should be 3.999.");
+  is(cue.endTime, 4, "Cue's end time should be 4.");
+  is(cue.text, "foo", "Cue's text should be foo.");
+
+  // Adding the same cue again should not increase the cue count.
+  trackElement.track.addCue(vttCue);
+  is(cueList.length, 7, "Cue list length should be 7.");
+
+  // Check that we are able to remove cues.
+  trackElement.track.removeCue(cue);
+  is(cueList.length, 6, "Cue list length should be 6.");
+}
+
+function checkRemoveNonExistCue() {
+  is(trackElement.track.cues.length, 6, "Cue list length should be 6.");
+  let exceptionHappened = false;
+  try {
+    // We should not be able to remove a cue that is not in the list.
+    trackElement.track.removeCue(new VTTCue(1, 2, "foo"));
+  } catch (e) {
+    // "NotFoundError" should be thrown when trying to remove a cue that is
+    // not in the list.
+    is(e.name, "NotFoundError", "Should have thrown NotFoundError.");
+    exceptionHappened = true;
+  }
+  // If this is false then we did not throw an error and probably removed a cue
+  // when we shouln't have.
+  ok(exceptionHappened, "Exception should have happened.");
+  is(trackElement.track.cues.length, 6, "Cue list length should still be 6.");
+}
+
+function checkActiveCues() {
+  video.currentTime = 2;
+  isnot(trackElement.track.activeCues, null);
+
+  trackElement.track.mode = "disabled";
+  is(trackElement.track.activeCues, null, "No active cue when track is disabled.");
+  trackElement.track.mode = "showing";
+}
+
+function checkCueRegion() {
+  let regionInfo = [
+    { lines: 2, width: 30 },
+    { lines: 4, width: 20 },
+    { lines: 2, width: 30 }
+  ];
+
+  for (let i = 0; i < regionInfo.length; i++) {
+    let cue = trackElement.track.cues[i];
+    isnot(cue.region, null, `Cue at ${i} should have a region.`);
+    for (let key in regionInfo[i]) {
+      is(cue.region[key], regionInfo[i][key],
+         `Region should have a ${key} property with a value of ${regionInfo[i][key]}`);
+    }
+  }
+}
+
+async function checkCActiveCuesDuringVideoPlaying() {
+  // Test TextTrack::ActiveCues.
+  let cueInfo = [
+    { startTime: 0.51, endTime: 0.71, ids: ["Cue 01"] },
+    { startTime: 0.72, endTime: 1.19, ids: [] },
+    { startTime: 1.2, endTime: 1.9, ids: [2] },
+    { startTime: 2, endTime: 2.4, ids: [2, 2.5] },
+    { startTime: 2.41, endTime: 2.70, ids: [2.5] },
+    { startTime: 2.71, endTime: 2.91, ids: [2.5, 3] },
+    { startTime: 2.92, endTime: 3.216, ids: [2.5] },
+    { startTime: 3.217, endTime: 3.5, ids: [2.5, 4, 5] },
+    { startTime: 3.51, endTime: 3.989, ids: [4, 5] },
+    { startTime: 3.99, endTime: 4, ids: [] }
+  ];
+
+  video.addEventListener("timeupdate", function() {
+    let activeCues = trackElement.track.activeCues,
+        found = false,
+        playbackTime = video.currentTime;
+
+    for (let i = 0; i < cueInfo.length; i++) {
+      let cue = cueInfo[i];
+      if (playbackTime >= cue.startTime && playbackTime < cue.endTime) {
+        is(activeCues.length, cue.ids.length, `There should be ${cue.ids.length} currently active cue(s).`);
+        for (let j = 0; j < cue.ids.length; j++) {
+          isnot(activeCues.getCueById(cue.ids[j]), undefined,
+                `The cue with ID ${cue.ids[j]} should be active.`);
         }
-      });
-
-      video.addEventListener("ended", function(){
-        SimpleTest.finish();
-      });
+        break;
+      }
+    }
+  });
 
-      video.play();
-    });
-  }
-);
+  info(`start video from 0s.`);
+  video.currentTime = 0;
+  video.play();
+  await once(video, "playing");
+  info(`video starts playing.`);
+  await once(video, "ended");
+}
 
 </script>
-</pre>
 </body>
 </html>
diff --git a/dom/media/test/test_texttrackregion.html b/dom/media/test/test_texttrackregion.html
index b2ab0199fc..f41c404445 100644
--- a/dom/media/test/test_texttrackregion.html
+++ b/dom/media/test/test_texttrackregion.html
@@ -1,64 +1,57 @@
 <!DOCTYPE HTML>
 <html>
-<!--
-https://bugzilla.mozilla.org/show_bug.cgi?id=917945
--->
 <head>
-  <meta charset='utf-8'>
   <title>Test for Bug 917945 - VTTRegion</title>
-  <script type="text/javascript" src="/MochiKit/MochiKit.js"></script>
   <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="manifest.js"></script>
   <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
 </head>
 <body>
-<p id="display"></p>
-<div id="content">
-</div>
-<pre id="test">
-<script class="testbody" type="text/javascript">
-SimpleTest.waitForExplicitFinish();
-SpecialPowers.pushPrefEnv({"set": [["media.webvtt.regions.enabled", true]]},
-  function() {
-    var video = document.createElement("video");
-    video.src = "seek.webm";
-    video.preload = "auto";
+<video id="v" src="seek.webm" preload="auto">
+  <track src="region.vtt" kind="subtitles" id="default" default>
+</video>
+<script type="text/javascript">
+/**
+ * This test is used to ensure that we can parse VTT region attributes correctly
+ * from vtt file.
+ */
+var trackElement = document.getElementById("default");
 
-    var trackElement = document.createElement("track");
-    trackElement.src = "region.vtt";
-    trackElement.kind = "subtitles";
+async function runTest() {
+  await waitUntiTrackLoaded();
+  checkRegionAttributes();
+  SimpleTest.finish();
+}
 
-    document.getElementById("content").appendChild(video);
-    video.appendChild(trackElement);
-    video.addEventListener("loadedmetadata", function run_tests() {
-      // Re-que run_tests() at the end of the event loop until the track
-      // element has loaded its data.
-      if (trackElement.readyState == 1) {
-        setTimeout(run_tests, 0);
-        return;
-      }
-      is(trackElement.readyState, 2, "Track::ReadyState should be set to LOADED.");
-
-      // Set mode to hidden so that the active cue lists are being updated.
-      trackElement.track.mode = "hidden";
+SimpleTest.waitForExplicitFinish();
+SpecialPowers.pushPrefEnv({"set": [["media.webvtt.regions.enabled", true]]},
+                            runTest);
+/**
+ * The following are test helper functions.
+ */
+async function waitUntiTrackLoaded() {
+  if (trackElement.readyState != 2) {
+    info(`wait until the track finishes loading`);
+    await once(trackElement, "load");
+  }
+  is(trackElement.readyState, 2, "Track::ReadyState should be set to LOADED.");
+}
 
-      var cues = trackElement.track.cues;
-      is(cues.length, 1, "Cue list length should be 1.");
+function checkRegionAttributes() {
+  let cues = trackElement.track.cues;
+  is(cues.length, 1, "Cue list length should be 1.");
 
-      var region = cues[0].region;
-      isnot(region, null, "Region should not be null.");
-      is(region.width, 62, "Region width should be 50.");
-      is(region.lines, 5, "Region lines should be 5.");
-      is(region.regionAnchorX, 4, "Region regionAnchorX should be 4.");
-      is(region.regionAnchorY, 78, "Region regionAnchorY should be 78.");
-      is(region.viewportAnchorX, 10, "Region viewportAnchorX should be 10.");
-      is(region.viewportAnchorY, 90, "Region viewportAnchorY should be 90.");
-      is(region.scroll, "up", "Region scroll should be 'up'");
+  let region = cues[0].region;
+  isnot(region, null, "Region should not be null.");
+  is(region.width, 62, "Region width should be 50.");
+  is(region.lines, 5, "Region lines should be 5.");
+  is(region.regionAnchorX, 4, "Region regionAnchorX should be 4.");
+  is(region.regionAnchorY, 78, "Region regionAnchorY should be 78.");
+  is(region.viewportAnchorX, 10, "Region viewportAnchorX should be 10.");
+  is(region.viewportAnchorY, 90, "Region viewportAnchorY should be 90.");
+  is(region.scroll, "up", "Region scroll should be 'up'");
+}
 
-      SimpleTest.finish();
-    });
-  }
-);
 </script>
-</pre>
 </body>
 </html>
diff --git a/dom/media/test/test_trackelementevent.html b/dom/media/test/test_trackelementevent.html
index 0e1a195aa1..f78033a89d 100644
--- a/dom/media/test/test_trackelementevent.html
+++ b/dom/media/test/test_trackelementevent.html
@@ -2,68 +2,76 @@
 <html>
 <head>
   <title>Test for Bug 882677 - Implement the 'sourcing out of band text tracks' algorithm</title>
-  <script type="text/javascript" src="/MochiKit/MochiKit.js"></script>
   <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="manifest.js"></script>
   <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
 </head>
 <body>
-<p id="display"></p>
-<div id="content" style="display: none">
-</div>
-<pre id="test">
-<script class="testbody" type="text/javascript">
-SimpleTest.waitForExplicitFinish();
-SpecialPowers.pushPrefEnv({"set": [["media.webvtt.regions.enabled", true]]},
-  function() {
-    var video = document.createElement("video");
-    video.src = "seek.webm";
-    video.preload = "auto";
+<video id="v" src="seek.webm" preload="auto">
+<script type="text/javascript">
+/**
+ * This test is used to ensure that we can load resource from vtt files correctly
+ * and will dispatch `error` event for invalid vtt files.
+ */
+var video = document.getElementById("v");
 
-    var trackOne = document.createElement("track");
-    trackOne.src = "basic.vtt";
-    trackOne.kind = "subtitles";
+async function runTest() {
+  let tracks = createTextTrackElements();
+  appendTracksToVideo(tracks);
+  await waitUntilsTrackLoadedOrGetError(tracks);
+  SimpleTest.finish()
+}
 
-    var trackTwo = document.createElement("track");
-    trackTwo.src = "bad-signature.vtt";
-    trackTwo.kind = "captions";
+SimpleTest.waitForExplicitFinish();
+onload = runTest;
 
-    var trackThree = document.createElement("track");
-    trackThree.src = "bad.vtt";
-    trackThree.kind = "chapters";
+/**
+ * The following are test helper functions.
+ */
+function createTextTrackElements() {
+  // Only first track has valid vtt resource, other tracks should get the error
+  // event because of invalid vtt resources.
+  let trackOne = document.createElement("track");
+  trackOne.src = "basic.vtt";
+  trackOne.kind = "subtitles";
+  trackOne.expectedLoaded = true;
 
-    var events = 0;
-    function trackOneEvent() {
-      ok(true, "A load event for trackOne should have happened.");
-      events++ && events == 3 && SimpleTest.finish();
-    }
-    function trackTwoEvent() {
-      ok(true, "An error event for trackTwo should have happened.");
-      events++ && events == 3 && SimpleTest.finish();
-    }
-    function trackThreeEvent() {
-      ok(true, "An error event for trackThree should have happened.");
-      events++ && events == 3 && SimpleTest.finish();
-    }
+  let trackTwo = document.createElement("track");
+  trackTwo.src = "bad-signature.vtt";
+  trackTwo.kind = "captions";
+  trackTwo.expectedLoaded = false;
 
-    function shouldNotBeCalled() {
-      ok(false, "Event should not have been called.");
-    }
+  let trackThree = document.createElement("track");
+  trackThree.src = "bad.vtt";
+  trackThree.kind = "chapters";
+  trackThree.expectedLoaded = false;
 
-    trackOne.addEventListener("load", trackOneEvent);
-    trackOne.addEventListener("error", shouldNotBeCalled)
-    trackTwo.addEventListener("load", shouldNotBeCalled);
-    trackTwo.addEventListener("error", trackTwoEvent);
-    trackThree.addEventListener("load", shouldNotBeCalled);
-    trackThree.addEventListener("error", trackThreeEvent);
+  return [trackOne, trackTwo, trackThree];
+}
 
-    document.getElementById("content").appendChild(video);
-    video.appendChild(trackOne);
-    video.appendChild(trackTwo);
-    video.appendChild(trackThree);
+function appendTracksToVideo(tracks) {
+  for (let track of tracks) {
+    video.appendChild(track);
   }
-);
+}
+
+async function waitUntilsTrackLoadedOrGetError(tracks) {
+  let promises = [];
+  for (let track of tracks) {
+    // explictly enable those track in order to start loading.
+    track.track.mode = "hidden";
+    if (track.expectedLoaded) {
+      info(`adding 'load' event to wait list.`);
+      promises.push(once(track, "load"));
+    } else {
+      info(`adding 'error' event to wait list.`);
+      promises.push(once(track, "error"));
+    }
+  }
+  info(`wait until tracks finish loading or get error.`);
+  await Promise.all(promises);
+  ok(true, "all tracks finish loading or get error.");
+}
 </script>
-</pre>
 </body>
 </html>
-
diff --git a/dom/media/webaudio/AudioWorkletImpl.h b/dom/media/webaudio/AudioWorkletImpl.h
index 7ae968b605..641ffc5457 100644
--- a/dom/media/webaudio/AudioWorkletImpl.h
+++ b/dom/media/webaudio/AudioWorkletImpl.h
@@ -28,6 +28,10 @@ class AudioWorkletImpl final : public WorkletImpl {
 
   nsresult SendControlMessage(already_AddRefed<nsIRunnable> aRunnable) override;
 
+  nsContentPolicyType ContentPolicyType() const override {
+    return nsIContentPolicy::TYPE_INTERNAL_AUDIOWORKLET;
+  }
+
   // Execution thread only.
   dom::AudioWorkletGlobalScope* GetGlobalScope() {
     return static_cast<dom::AudioWorkletGlobalScope*>(
diff --git a/dom/media/webaudio/WebAudioUtils.cpp b/dom/media/webaudio/WebAudioUtils.cpp
index c46f847285..49c5c61fb6 100644
--- a/dom/media/webaudio/WebAudioUtils.cpp
+++ b/dom/media/webaudio/WebAudioUtils.cpp
@@ -6,6 +6,7 @@
 #include "AudioNodeTrack.h"
 #include "blink/HRTFDatabaseLoader.h"
 
+#include "nsComponentManagerUtils.h"
 #include "nsContentUtils.h"
 #include "nsIConsoleService.h"
 #include "nsIScriptError.h"
diff --git a/dom/media/webvtt/WebVTTParserWrapper.jsm b/dom/media/webvtt/WebVTTParserWrapper.jsm
index 5156fc18ec..6b14056e3f 100644
--- a/dom/media/webvtt/WebVTTParserWrapper.jsm
+++ b/dom/media/webvtt/WebVTTParserWrapper.jsm
@@ -43,6 +43,12 @@ WebVTTParserWrapper.prototype =
     };
   },
 
+  cancel: function() {
+    this.parser.oncue = null;
+    this.parser.onregion = null;
+    this.parser.onparsingerror = null;
+  },
+
   convertCueToDOMTree: function(window, cue)
   {
     return WebVTT.convertCueToDOMTree(window, cue.text);
diff --git a/dom/media/webvtt/nsIWebVTTParserWrapper.idl b/dom/media/webvtt/nsIWebVTTParserWrapper.idl
index 5d603b3b3c..48406e63d3 100644
--- a/dom/media/webvtt/nsIWebVTTParserWrapper.idl
+++ b/dom/media/webvtt/nsIWebVTTParserWrapper.idl
@@ -52,6 +52,11 @@ interface nsIWebVTTParserWrapper : nsISupports
    */
   void watch(in nsIWebVTTListener callback);
 
+  /**
+   * Cancel watching notifications which parser would send.
+   */
+  void cancel();
+
   /**
    * Convert the text content of a WebVTT cue to a document fragment so that
    * we can display it on the page.
diff --git a/dom/midi/MIDIUtils.cpp b/dom/midi/MIDIUtils.cpp
index c52bc3b6f7..0b654517ec 100644
--- a/dom/midi/MIDIUtils.cpp
+++ b/dom/midi/MIDIUtils.cpp
@@ -4,6 +4,7 @@
 
 #include "mozilla/dom/MIDITypes.h"
 #include "mozilla/dom/MIDIUtils.h"
+#include "mozilla/UniquePtr.h"
 
 // Taken from MIDI IMPLEMENTATION CHART INSTRUCTIONS, MIDI Spec v1.0, Pg. 97
 static const uint8_t kCommandByte = 0x80;
@@ -76,7 +77,7 @@ uint32_t ParseMessages(const nsTArray<uint8_t>& aByteBuffer,
                        nsTArray<MIDIMessage>& aMsgArray) {
   uint32_t bytesRead = 0;
   bool inSysexMessage = false;
-  nsAutoPtr<MIDIMessage> currentMsg;
+  UniquePtr<MIDIMessage> currentMsg;
   for (auto& byte : aByteBuffer) {
     bytesRead++;
     if ((byte & kSystemRealtimeMessage) == kSystemRealtimeMessage) {
@@ -94,10 +95,10 @@ uint32_t ParseMessages(const nsTArray<uint8_t>& aByteBuffer,
       }
       inSysexMessage = false;
     } else if (byte & kCommandByte) {
-      if (currentMsg && IsValidMessage(currentMsg)) {
+      if (currentMsg && IsValidMessage(currentMsg.get())) {
         aMsgArray.AppendElement(*currentMsg);
       }
-      currentMsg = new MIDIMessage();
+      currentMsg = MakeUnique<MIDIMessage>();
       currentMsg->timestamp() = aTimestamp;
     }
     currentMsg->data().AppendElement(byte);
@@ -105,7 +106,7 @@ uint32_t ParseMessages(const nsTArray<uint8_t>& aByteBuffer,
       inSysexMessage = true;
     }
   }
-  if (currentMsg && IsValidMessage(currentMsg)) {
+  if (currentMsg && IsValidMessage(currentMsg.get())) {
     aMsgArray.AppendElement(*currentMsg);
   }
   return bytesRead;
diff --git a/dom/network/TCPServerSocket.cpp b/dom/network/TCPServerSocket.cpp
index 78470e9e40..50f8b5cab5 100644
--- a/dom/network/TCPServerSocket.cpp
+++ b/dom/network/TCPServerSocket.cpp
@@ -11,6 +11,7 @@
 #include "mozilla/ErrorResult.h"
 #include "TCPServerSocket.h"
 #include "TCPSocket.h"
+#include "nsComponentManagerUtils.h"
 
 using namespace mozilla::dom;
 
diff --git a/dom/notification/Notification.cpp b/dom/notification/Notification.cpp
index 6dea253cc8..5e5e31f4f3 100644
--- a/dom/notification/Notification.cpp
+++ b/dom/notification/Notification.cpp
@@ -9,7 +9,7 @@
 #include "mozilla/Encoding.h"
 #include "mozilla/EventStateManager.h"
 #include "mozilla/JSONWriter.h"
-#include "mozilla/Move.h"
+#include <utility>
 #include "mozilla/OwningNonNull.h"
 #include "mozilla/Preferences.h"
 #include "mozilla/Services.h"
@@ -1295,7 +1295,7 @@ void Notification::ShowInternal() {
   // Transfer ownership to local scope so we can either release it at the end
   // of this function or transfer it to the observer.
   UniquePtr<NotificationRef> ownership;
-  mozilla::Swap(ownership, mTempRef);
+  std::swap(ownership, mTempRef);
   MOZ_ASSERT(ownership->GetNotification() == this);
 
   nsresult rv = PersistNotification();
@@ -1834,7 +1834,7 @@ void Notification::CloseInternal() {
   // of this function. This is relevant when the call is from
   // NotificationTask::Run().
   UniquePtr<NotificationRef> ownership;
-  mozilla::Swap(ownership, mTempRef);
+  std::swap(ownership, mTempRef);
 
   SetAlertName();
   UnpersistNotification();
diff --git a/dom/performance/PerformanceTiming.cpp b/dom/performance/PerformanceTiming.cpp
index f7f789e927..bdb0b46e7d 100644
--- a/dom/performance/PerformanceTiming.cpp
+++ b/dom/performance/PerformanceTiming.cpp
@@ -273,7 +273,7 @@ bool PerformanceTimingData::CheckAllowedOrigin(nsIHttpChannel* aResourceChannel,
     return true;
   }
 
-  nsCOMPtr<nsIPrincipal> principal = loadInfo->LoadingPrincipal();
+  nsCOMPtr<nsIPrincipal> principal = loadInfo->GetLoadingPrincipal();
 
   // Check if the resource is either same origin as the page that started
   // the load, or if the response contains the proper Timing-Allow-Origin
diff --git a/dom/plugins/base/nsPluginDirServiceProvider.cpp b/dom/plugins/base/nsPluginDirServiceProvider.cpp
index df0c81632b..be482a4fb0 100644
--- a/dom/plugins/base/nsPluginDirServiceProvider.cpp
+++ b/dom/plugins/base/nsPluginDirServiceProvider.cpp
@@ -4,6 +4,7 @@
 
 #include "nsPluginDirServiceProvider.h"
 
+#include "nsComponentManagerUtils.h"
 #include "nsCRT.h"
 #include "nsIFile.h"
 #include "nsDependentString.h"
@@ -15,6 +16,150 @@
 
 using namespace mozilla;
 
+typedef struct structVer {
+  WORD wMajor;
+  WORD wMinor;
+  WORD wRelease;
+  WORD wBuild;
+} verBlock;
+
+static void ClearVersion(verBlock* ver) {
+  ver->wMajor = 0;
+  ver->wMinor = 0;
+  ver->wRelease = 0;
+  ver->wBuild = 0;
+}
+
+static BOOL FileExists(LPCWSTR szFile) {
+  return GetFileAttributesW(szFile) != 0xFFFFFFFF;
+}
+
+// Get file version information from a file
+static BOOL GetFileVersion(LPCWSTR szFile, verBlock* vbVersion) {
+  UINT uLen;
+  UINT dwLen;
+  BOOL bRv;
+  DWORD dwHandle;
+  LPVOID lpData;
+  LPVOID lpBuffer;
+  VS_FIXEDFILEINFO* lpBuffer2;
+
+  ClearVersion(vbVersion);
+  if (FileExists(szFile)) {
+    bRv = TRUE;
+    LPCWSTR lpFilepath = szFile;
+    dwLen = GetFileVersionInfoSizeW(lpFilepath, &dwHandle);
+    lpData = (LPVOID)malloc(dwLen);
+    uLen = 0;
+
+    if (lpData &&
+        GetFileVersionInfoW(lpFilepath, dwHandle, dwLen, lpData) != 0) {
+      if (VerQueryValueW(lpData, L"\\", &lpBuffer, &uLen) != 0) {
+        lpBuffer2 = (VS_FIXEDFILEINFO*)lpBuffer;
+
+        vbVersion->wMajor = HIWORD(lpBuffer2->dwFileVersionMS);
+        vbVersion->wMinor = LOWORD(lpBuffer2->dwFileVersionMS);
+        vbVersion->wRelease = HIWORD(lpBuffer2->dwFileVersionLS);
+        vbVersion->wBuild = LOWORD(lpBuffer2->dwFileVersionLS);
+      }
+    }
+
+    free(lpData);
+  } else {
+    /* File does not exist */
+    bRv = FALSE;
+  }
+
+  return bRv;
+}
+
+// Will deep copy ver2 into ver1
+static void CopyVersion(verBlock* ver1, verBlock* ver2) {
+  ver1->wMajor = ver2->wMajor;
+  ver1->wMinor = ver2->wMinor;
+  ver1->wRelease = ver2->wRelease;
+  ver1->wBuild = ver2->wBuild;
+}
+
+// Convert a string version to a version struct
+static void TranslateVersionStr(const WCHAR* szVersion, verBlock* vbVersion) {
+  WCHAR* szNum1 = nullptr;
+  WCHAR* szNum2 = nullptr;
+  WCHAR* szNum3 = nullptr;
+  WCHAR* szNum4 = nullptr;
+  WCHAR* szJavaBuild = nullptr;
+
+  WCHAR* strVer = nullptr;
+  if (szVersion) {
+    strVer = wcsdup(szVersion);
+  }
+
+  if (!strVer) {
+    // Out of memory
+    ClearVersion(vbVersion);
+    return;
+  }
+
+  // Java may be using an underscore instead of a dot for the build ID
+  szJavaBuild = wcschr(strVer, '_');
+  if (szJavaBuild) {
+    szJavaBuild[0] = '.';
+  }
+
+#if defined(__MINGW32__)
+  // MSVC 2013 and earlier provided only a non-standard two-argument variant of
+  // wcstok that is generally not thread-safe. For our purposes here, it works
+  // fine, though.
+  auto wcstok = [](wchar_t* strToken, const wchar_t* strDelimit,
+                   wchar_t** /*ctx*/) {
+    return ::std::wcstok(strToken, strDelimit);
+  };
+#endif
+
+  wchar_t* ctx = nullptr;
+  szNum1 = wcstok(strVer, L".", &ctx);
+  szNum2 = wcstok(nullptr, L".", &ctx);
+  szNum3 = wcstok(nullptr, L".", &ctx);
+  szNum4 = wcstok(nullptr, L".", &ctx);
+
+  vbVersion->wMajor = szNum1 ? (WORD)_wtoi(szNum1) : 0;
+  vbVersion->wMinor = szNum2 ? (WORD)_wtoi(szNum2) : 0;
+  vbVersion->wRelease = szNum3 ? (WORD)_wtoi(szNum3) : 0;
+  vbVersion->wBuild = szNum4 ? (WORD)_wtoi(szNum4) : 0;
+
+  free(strVer);
+}
+
+// Compare two version struct, return zero if the same
+static int CompareVersion(verBlock vbVersionOld, verBlock vbVersionNew) {
+  if (vbVersionOld.wMajor > vbVersionNew.wMajor) {
+    return 4;
+  } else if (vbVersionOld.wMajor < vbVersionNew.wMajor) {
+    return -4;
+  }
+
+  if (vbVersionOld.wMinor > vbVersionNew.wMinor) {
+    return 3;
+  } else if (vbVersionOld.wMinor < vbVersionNew.wMinor) {
+    return -3;
+  }
+
+  if (vbVersionOld.wRelease > vbVersionNew.wRelease) {
+    return 2;
+  } else if (vbVersionOld.wRelease < vbVersionNew.wRelease) {
+    return -2;
+  }
+
+  if (vbVersionOld.wBuild > vbVersionNew.wBuild) {
+    return 1;
+  } else if (vbVersionOld.wBuild < vbVersionNew.wBuild) {
+    return -1;
+  }
+
+  /* the versions are all the same */
+  return 0;
+}
+
 //*****************************************************************************
 // nsPluginDirServiceProvider::Constructor/Destructor
 //*****************************************************************************
@@ -36,12 +181,171 @@ NS_IMPL_ISUPPORTS(nsPluginDirServiceProvider, nsIDirectoryServiceProvider)
 NS_IMETHODIMP
 nsPluginDirServiceProvider::GetFile(const char* charProp, bool* persistant,
                                     nsIFile** _retval) {
+  nsCOMPtr<nsIFile> localFile;
+  nsresult rv = NS_ERROR_FAILURE;
+
   NS_ENSURE_ARG(charProp);
 
   *_retval = nullptr;
   *persistant = false;
 
-  return NS_ERROR_FAILURE;
+  nsCOMPtr<nsIWindowsRegKey> regKey =
+      do_CreateInstance("@mozilla.org/windows-registry-key;1");
+  NS_ENSURE_TRUE(regKey, NS_ERROR_FAILURE);
+
+  if (nsCRT::strcmp(charProp, NS_WIN_QUICKTIME_SCAN_KEY) == 0) {
+    nsAutoCString strVer;
+    Preferences::GetCString(charProp, strVer);
+    if (strVer.IsEmpty()) {
+      return NS_ERROR_FAILURE;
+    }
+    verBlock minVer;
+    TranslateVersionStr(NS_ConvertASCIItoUTF16(strVer).get(), &minVer);
+
+    // Look for the Quicktime system installation plugins directory
+    verBlock qtVer;
+    ClearVersion(&qtVer);
+
+    // First we need to check the version of Quicktime via checking
+    // the EXE's version table
+    rv =
+        regKey->Open(nsIWindowsRegKey::ROOT_KEY_LOCAL_MACHINE,
+                     NS_LITERAL_STRING("software\\Microsoft\\Windows\\CurrentVe"
+                                       "rsion\\App Paths\\QuickTimePlayer.exe"),
+                     nsIWindowsRegKey::ACCESS_READ);
+    if (NS_SUCCEEDED(rv)) {
+      nsAutoString path;
+      rv = regKey->ReadStringValue(NS_LITERAL_STRING(""), path);
+      if (NS_SUCCEEDED(rv)) {
+        GetFileVersion(path.get(), &qtVer);
+      }
+      regKey->Close();
+    }
+    if (CompareVersion(qtVer, minVer) < 0) return rv;
+
+    rv = regKey->Open(
+        nsIWindowsRegKey::ROOT_KEY_LOCAL_MACHINE,
+        NS_LITERAL_STRING("software\\Apple Computer, Inc.\\QuickTime"),
+        nsIWindowsRegKey::ACCESS_READ);
+    if (NS_SUCCEEDED(rv)) {
+      nsAutoString path;
+      rv = regKey->ReadStringValue(NS_LITERAL_STRING("InstallDir"), path);
+      if (NS_SUCCEEDED(rv)) {
+        path += NS_LITERAL_STRING("\\Plugins");
+        rv = NS_NewLocalFile(path, true, getter_AddRefs(localFile));
+      }
+    }
+  } else if (nsCRT::strcmp(charProp, NS_WIN_WMP_SCAN_KEY) == 0) {
+    nsAutoCString strVer;
+    Preferences::GetCString(charProp, strVer);
+    if (strVer.IsEmpty()) {
+      return NS_ERROR_FAILURE;
+    }
+    verBlock minVer;
+    TranslateVersionStr(NS_ConvertASCIItoUTF16(strVer).get(), &minVer);
+
+    // Look for Windows Media Player system installation plugins directory
+    verBlock wmpVer;
+    ClearVersion(&wmpVer);
+
+    // First we need to check the version of WMP
+    rv = regKey->Open(nsIWindowsRegKey::ROOT_KEY_LOCAL_MACHINE,
+                      NS_LITERAL_STRING("software\\Microsoft\\Windows\\CurrentV"
+                                        "ersion\\App Paths\\wmplayer.exe"),
+                      nsIWindowsRegKey::ACCESS_READ);
+    if (NS_SUCCEEDED(rv)) {
+      nsAutoString path;
+      rv = regKey->ReadStringValue(NS_LITERAL_STRING(""), path);
+      if (NS_SUCCEEDED(rv)) {
+        GetFileVersion(path.get(), &wmpVer);
+      }
+      regKey->Close();
+    }
+    if (CompareVersion(wmpVer, minVer) < 0) return rv;
+
+    rv = regKey->Open(nsIWindowsRegKey::ROOT_KEY_LOCAL_MACHINE,
+                      NS_LITERAL_STRING("software\\Microsoft\\MediaPlayer"),
+                      nsIWindowsRegKey::ACCESS_READ);
+    if (NS_SUCCEEDED(rv)) {
+      nsAutoString path;
+      rv = regKey->ReadStringValue(NS_LITERAL_STRING("Installation Directory"),
+                                   path);
+      if (NS_SUCCEEDED(rv)) {
+        rv = NS_NewLocalFile(path, true, getter_AddRefs(localFile));
+      }
+    }
+  } else if (nsCRT::strcmp(charProp, NS_WIN_ACROBAT_SCAN_KEY) == 0) {
+    nsAutoCString strVer;
+    Preferences::GetCString(charProp, strVer);
+    if (strVer.IsEmpty()) {
+      return NS_ERROR_FAILURE;
+    }
+
+    verBlock minVer;
+    TranslateVersionStr(NS_ConvertASCIItoUTF16(strVer).get(), &minVer);
+
+    // Look for Adobe Acrobat system installation plugins directory
+    verBlock maxVer;
+    ClearVersion(&maxVer);
+
+    nsAutoString newestPath;
+
+    rv = regKey->Open(nsIWindowsRegKey::ROOT_KEY_LOCAL_MACHINE,
+                      NS_LITERAL_STRING("software\\Adobe\\Acrobat Reader"),
+                      nsIWindowsRegKey::ACCESS_READ);
+    if (NS_FAILED(rv)) {
+      rv = regKey->Open(nsIWindowsRegKey::ROOT_KEY_LOCAL_MACHINE,
+                        NS_LITERAL_STRING("software\\Adobe\\Adobe Acrobat"),
+                        nsIWindowsRegKey::ACCESS_READ);
+      if (NS_FAILED(rv)) {
+        return NS_ERROR_FAILURE;
+      }
+    }
+
+    // We must enumerate through the keys because what if there is
+    // more than one version?
+    uint32_t childCount = 0;
+    regKey->GetChildCount(&childCount);
+
+    for (uint32_t index = 0; index < childCount; ++index) {
+      nsAutoString childName;
+      rv = regKey->GetChildName(index, childName);
+      if (NS_SUCCEEDED(rv)) {
+        verBlock curVer;
+        TranslateVersionStr(childName.get(), &curVer);
+
+        childName += NS_LITERAL_STRING("\\InstallPath");
+
+        nsCOMPtr<nsIWindowsRegKey> childKey;
+        rv = regKey->OpenChild(childName, nsIWindowsRegKey::ACCESS_QUERY_VALUE,
+                               getter_AddRefs(childKey));
+        if (NS_SUCCEEDED(rv)) {
+          // We have a sub key
+          nsAutoString path;
+          rv = childKey->ReadStringValue(NS_LITERAL_STRING(""), path);
+          if (NS_SUCCEEDED(rv)) {
+            if (CompareVersion(curVer, maxVer) >= 0 &&
+                CompareVersion(curVer, minVer) >= 0) {
+              newestPath = path;
+              CopyVersion(&maxVer, &curVer);
+            }
+          }
+        }
+      }
+    }
+
+    if (!newestPath.IsEmpty()) {
+      newestPath += NS_LITERAL_STRING("\\browser");
+      rv = NS_NewLocalFile(newestPath, true, getter_AddRefs(localFile));
+    }
+  }
+
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  localFile.forget(_retval);
+  return NS_OK;
 }
 
 nsresult nsPluginDirServiceProvider::GetPLIDDirectories(
diff --git a/dom/plugins/base/nsPluginDirServiceProvider.h b/dom/plugins/base/nsPluginDirServiceProvider.h
index 1eb15dbc8a..7c682ea658 100644
--- a/dom/plugins/base/nsPluginDirServiceProvider.h
+++ b/dom/plugins/base/nsPluginDirServiceProvider.h
@@ -13,6 +13,12 @@
 
 class nsISimpleEnumerator;
 
+// Note: Our directory service provider scan keys are prefs which are check
+//       for minimum versions compatibility
+#define NS_WIN_ACROBAT_SCAN_KEY        "plugin.scan.Acrobat"
+#define NS_WIN_QUICKTIME_SCAN_KEY      "plugin.scan.Quicktime"
+#define NS_WIN_WMP_SCAN_KEY            "plugin.scan.WindowsMediaPlayer"
+
 //*****************************************************************************
 // class nsPluginDirServiceProvider
 //*****************************************************************************
diff --git a/dom/plugins/base/nsPluginHost.cpp b/dom/plugins/base/nsPluginHost.cpp
index 36747c3631..255f8f13d0 100644
--- a/dom/plugins/base/nsPluginHost.cpp
+++ b/dom/plugins/base/nsPluginHost.cpp
@@ -1873,35 +1873,6 @@ struct CompareFilesByTime {
 
 }  // namespace
 
-static bool ShouldAddPlugin(const nsPluginInfo& info, bool flashOnly) {
-  if (!info.fName ||
-      (strcmp(info.fName, "Shockwave Flash") != 0 && flashOnly)) {
-    return false;
-  }
-  for (uint32_t i = 0; i < info.fVariantCount; ++i) {
-    if (info.fMimeTypeArray[i] &&
-        (!strcmp(info.fMimeTypeArray[i], "application/x-shockwave-flash") ||
-         !strcmp(info.fMimeTypeArray[i],
-                 "application/x-shockwave-flash-test"))) {
-      return true;
-    }
-    if (flashOnly) {
-      continue;
-    }
-    if (info.fMimeTypeArray[i] &&
-        (!strcmp(info.fMimeTypeArray[i], "application/x-test") ||
-         !strcmp(info.fMimeTypeArray[i], "application/x-Second-Test"))) {
-      return true;
-    }
-  }
-#ifdef PLUGIN_LOGGING
-  PLUGIN_LOG(PLUGIN_LOG_NORMAL,
-             ("ShouldAddPlugin : Ignoring non-flash plugin library %s\n",
-              aPluginTag->FileName().get()));
-#endif  // PLUGIN_LOGGING
-  return false;
-}
-
 void nsPluginHost::AddPluginTag(nsPluginTag* aPluginTag) {
   aPluginTag->mNext = mPlugins;
   mPlugins = aPluginTag;
@@ -1937,8 +1908,6 @@ nsresult nsPluginHost::ScanPluginsDirectory(nsIFile* pluginsDir,
              ("nsPluginHost::ScanPluginsDirectory dir=%s\n", dirPath.get()));
 #endif
 
-  bool flashOnly = Preferences::GetBool("plugin.load_flash_only", true);
-
   nsCOMPtr<nsIDirectoryEnumerator> iter;
   rv = pluginsDir->GetDirectoryEntries(getter_AddRefs(iter));
   if (NS_FAILED(rv)) return rv;
@@ -2036,8 +2005,7 @@ nsresult nsPluginHost::ScanPluginsDirectory(nsIFile* pluginsDir,
         res = pluginFile.GetPluginInfo(info, &library);
       }
       // if we don't have mime type don't proceed, this is not a plugin
-      if (NS_FAILED(res) || !info.fMimeTypeArray ||
-          (!ShouldAddPlugin(info, flashOnly))) {
+      if (NS_FAILED(res) || !info.fMimeTypeArray) {
         RefPtr<nsInvalidPluginTag> invalidTag =
             new nsInvalidPluginTag(filePath.get(), fileModTime);
         pluginFile.FreePluginInfo(info);
@@ -2373,6 +2341,35 @@ nsresult nsPluginHost::FindPlugins(bool aCreatePluginList,
       }
     }
   }
+
+  // Scan the installation paths of our popular plugins if the prefs are enabled
+
+  // This table controls the order of scanning
+  const char* const prefs[] = {NS_WIN_ACROBAT_SCAN_KEY,
+                               NS_WIN_QUICKTIME_SCAN_KEY, NS_WIN_WMP_SCAN_KEY};
+
+  uint32_t size = sizeof(prefs) / sizeof(prefs[0]);
+
+  for (uint32_t i = 0; i < size; i += 1) {
+    nsCOMPtr<nsIFile> dirToScan;
+    bool bExists;
+    if (NS_SUCCEEDED(dirService->Get(prefs[i], NS_GET_IID(nsIFile),
+                                     getter_AddRefs(dirToScan))) &&
+        dirToScan && NS_SUCCEEDED(dirToScan->Exists(&bExists)) && bExists) {
+      ScanPluginsDirectory(dirToScan, aCreatePluginList, &pluginschanged);
+
+      if (pluginschanged) *aPluginsChanged = true;
+
+      // if we are just looking for possible changes,
+      // no need to proceed if changes are detected
+      if (!aCreatePluginList && *aPluginsChanged) {
+        NS_ITERATIVE_UNREF_LIST(RefPtr<nsPluginTag>, mCachedPlugins, mNext);
+        NS_ITERATIVE_UNREF_LIST(RefPtr<nsInvalidPluginTag>, mInvalidPlugins,
+                                mNext);
+        return NS_OK;
+      }
+    }
+  }
 #endif
 
   // We should also consider plugins to have changed if any plugins have been
@@ -2624,17 +2621,14 @@ nsresult nsPluginHost::WritePluginInfo() {
     return rv;
   }
 
-  bool flashOnly = Preferences::GetBool("plugin.load_flash_only", true);
-
   PR_fprintf(fd, "Generated File. Do not edit.\n");
 
-  PR_fprintf(fd, "\n[HEADER]\nVersion%c%s%c%c%c\nArch%c%s%c%c\n",
-             PLUGIN_REGISTRY_FIELD_DELIMITER, kPluginRegistryVersion,
-             flashOnly ? 't' : 'f', PLUGIN_REGISTRY_FIELD_DELIMITER,
-             PLUGIN_REGISTRY_END_OF_LINE_MARKER,
-             PLUGIN_REGISTRY_FIELD_DELIMITER, arch.get(),
-             PLUGIN_REGISTRY_FIELD_DELIMITER,
-             PLUGIN_REGISTRY_END_OF_LINE_MARKER);
+  PR_fprintf(
+      fd, "\n[HEADER]\nVersion%c%s%c%c\nArch%c%s%c%c\n",
+      PLUGIN_REGISTRY_FIELD_DELIMITER, kPluginRegistryVersion,
+      PLUGIN_REGISTRY_FIELD_DELIMITER, PLUGIN_REGISTRY_END_OF_LINE_MARKER,
+      PLUGIN_REGISTRY_FIELD_DELIMITER, arch.get(),
+      PLUGIN_REGISTRY_FIELD_DELIMITER, PLUGIN_REGISTRY_END_OF_LINE_MARKER);
 
   // Store all plugins in the mPlugins list - all plugins currently in use.
   PR_fprintf(fd, "\n[PLUGINS]\n");
@@ -2801,10 +2795,7 @@ nsresult nsPluginHost::ReadPluginInfo() {
   if (PL_strcmp(values[0], "Version")) return rv;
 
   // If we're reading an old registry, ignore it
-  // If we flipped the flash-only pref, ignore it
-  bool flashOnly = Preferences::GetBool("plugin.load_flash_only", true);
   nsAutoCString expectedVersion(kPluginRegistryVersion);
-  expectedVersion.Append(flashOnly ? 't' : 'f');
 
   if (!expectedVersion.Equals(values[1])) {
     return rv;
diff --git a/dom/plugins/base/nsPluginStreamListenerPeer.cpp b/dom/plugins/base/nsPluginStreamListenerPeer.cpp
index f0ad3f39f8..10b7f03c54 100644
--- a/dom/plugins/base/nsPluginStreamListenerPeer.cpp
+++ b/dom/plugins/base/nsPluginStreamListenerPeer.cpp
@@ -225,7 +225,6 @@ nsPluginStreamListenerPeer::OnStartRequest(nsIRequest* request) {
 }
 
 NS_IMETHODIMP nsPluginStreamListenerPeer::OnProgress(nsIRequest* request,
-                                                     nsISupports* aContext,
                                                      int64_t aProgress,
                                                      int64_t aProgressMax) {
   nsresult rv = NS_OK;
@@ -233,7 +232,6 @@ NS_IMETHODIMP nsPluginStreamListenerPeer::OnProgress(nsIRequest* request,
 }
 
 NS_IMETHODIMP nsPluginStreamListenerPeer::OnStatus(nsIRequest* request,
-                                                   nsISupports* aContext,
                                                    nsresult aStatus,
                                                    const char16_t* aStatusArg) {
   return NS_OK;
diff --git a/dom/presentation/PresentationDeviceManager.cpp b/dom/presentation/PresentationDeviceManager.cpp
index 23fbdb7851..45d5612003 100644
--- a/dom/presentation/PresentationDeviceManager.cpp
+++ b/dom/presentation/PresentationDeviceManager.cpp
@@ -9,6 +9,7 @@
 #include "nsArrayUtils.h"
 #include "nsCategoryCache.h"
 #include "nsCOMPtr.h"
+#include "nsComponentManagerUtils.h"
 #include "nsIMutableArray.h"
 #include "nsIObserverService.h"
 #include "nsISupportsPrimitives.h"
diff --git a/dom/presentation/PresentationRequest.cpp b/dom/presentation/PresentationRequest.cpp
index bb8f564335..5c58a962a9 100644
--- a/dom/presentation/PresentationRequest.cpp
+++ b/dom/presentation/PresentationRequest.cpp
@@ -4,29 +4,30 @@
 
 #include "PresentationRequest.h"
 
+#include <utility>
+
 #include "AvailabilityCollection.h"
 #include "ControllerConnectionCollection.h"
+#include "Presentation.h"
+#include "PresentationAvailability.h"
+#include "PresentationCallbacks.h"
+#include "PresentationLog.h"
+#include "PresentationTransportBuilderConstructor.h"
 #include "mozilla/BasePrincipal.h"
+#include "mozilla/dom/Document.h"
 #include "mozilla/dom/Navigator.h"
-#include "mozilla/dom/PresentationRequestBinding.h"
 #include "mozilla/dom/PresentationConnectionAvailableEvent.h"
+#include "mozilla/dom/PresentationRequestBinding.h"
 #include "mozilla/dom/Promise.h"
-#include "mozilla/Move.h"
 #include "nsContentSecurityManager.h"
 #include "nsCycleCollectionParticipant.h"
 #include "nsGlobalWindow.h"
-#include "mozilla/dom/Document.h"
 #include "nsIPresentationService.h"
 #include "nsIURI.h"
 #include "nsIUUIDGenerator.h"
 #include "nsNetUtil.h"
 #include "nsSandboxFlags.h"
 #include "nsServiceManagerUtils.h"
-#include "Presentation.h"
-#include "PresentationAvailability.h"
-#include "PresentationCallbacks.h"
-#include "PresentationLog.h"
-#include "PresentationTransportBuilderConstructor.h"
 
 using namespace mozilla;
 using namespace mozilla::dom;
diff --git a/dom/presentation/PresentationSessionInfo.cpp b/dom/presentation/PresentationSessionInfo.cpp
index 4a82cd39b5..a32b3ac9ba 100644
--- a/dom/presentation/PresentationSessionInfo.cpp
+++ b/dom/presentation/PresentationSessionInfo.cpp
@@ -2,17 +2,23 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-#include "mozilla/dom/ContentParent.h"
-#include "mozilla/dom/HTMLIFrameElementBinding.h"
-#include "mozilla/dom/BrowserParent.h"
+#include "PresentationSessionInfo.h"
+
+#include <utility>
+
+#include "PresentationLog.h"
+#include "PresentationService.h"
 #include "mozilla/Logging.h"
-#include "mozilla/Move.h"
 #include "mozilla/Preferences.h"
+#include "mozilla/dom/BrowserParent.h"
+#include "mozilla/dom/ContentParent.h"
+#include "mozilla/dom/ElementBinding.h"
+#include "mozilla/dom/HTMLIFrameElementBinding.h"
 #include "nsContentUtils.h"
-#include "nsGlobalWindow.h"
-#include "nsIDocShell.h"
 #include "nsFrameLoader.h"
 #include "nsFrameLoaderOwner.h"
+#include "nsGlobalWindow.h"
+#include "nsIDocShell.h"
 #include "nsIMutableArray.h"
 #include "nsINetAddr.h"
 #include "nsISocketTransport.h"
@@ -21,9 +27,6 @@
 #include "nsQueryObject.h"
 #include "nsServiceManagerUtils.h"
 #include "nsThreadUtils.h"
-#include "PresentationLog.h"
-#include "PresentationService.h"
-#include "PresentationSessionInfo.h"
 
 #ifdef MOZ_WIDGET_ANDROID
 #  include "nsIPresentationNetworkHelper.h"
diff --git a/dom/prototype/PrototypeDocumentContentSink.cpp b/dom/prototype/PrototypeDocumentContentSink.cpp
index cf75134364..fdbe972459 100644
--- a/dom/prototype/PrototypeDocumentContentSink.cpp
+++ b/dom/prototype/PrototypeDocumentContentSink.cpp
@@ -9,7 +9,6 @@
 #include "nsIContent.h"
 #include "nsIURI.h"
 #include "nsNetUtil.h"
-#include "nsIStyleSheetLinkingElement.h"
 #include "nsHTMLParts.h"
 #include "nsCRT.h"
 #include "mozilla/StyleSheetInlines.h"
@@ -24,7 +23,6 @@
 #include "mozilla/Logging.h"
 #include "nsRect.h"
 #include "nsIScriptElement.h"
-#include "nsStyleLinkElement.h"
 #include "nsReadableUtils.h"
 #include "nsUnicharUtils.h"
 #include "nsIChannel.h"
@@ -44,6 +42,7 @@
 #include "mozilla/dom/Element.h"
 #include "mozilla/dom/HTMLTemplateElement.h"
 #include "mozilla/dom/ProcessingInstruction.h"
+#include "mozilla/dom/XMLStylesheetProcessingInstruction.h"
 #include "mozilla/dom/ScriptLoader.h"
 #include "mozilla/LoadInfo.h"
 #include "mozilla/PresShell.h"
@@ -343,7 +342,10 @@ nsresult PrototypeDocumentContentSink::CreateAndInsertPI(
 
   nsresult rv;
   if (aProtoPI->mTarget.EqualsLiteral("xml-stylesheet")) {
-    rv = InsertXMLStylesheetPI(aProtoPI, aParent, aBeforeThis, node);
+    MOZ_ASSERT(LinkStyle::FromNode(*node),
+               "XML Stylesheet node does not implement LinkStyle!");
+    auto* pi = static_cast<XMLStylesheetProcessingInstruction*>(node.get());
+    rv = InsertXMLStylesheetPI(aProtoPI, aParent, aBeforeThis, pi);
   } else {
     // No special processing, just add the PI to the document.
     rv = aParent->InsertChildBefore(
@@ -356,30 +358,24 @@ nsresult PrototypeDocumentContentSink::CreateAndInsertPI(
 
 nsresult PrototypeDocumentContentSink::InsertXMLStylesheetPI(
     const nsXULPrototypePI* aProtoPI, nsINode* aParent, nsINode* aBeforeThis,
-    nsIContent* aPINode) {
-  nsCOMPtr<nsIStyleSheetLinkingElement> ssle(do_QueryInterface(aPINode));
-  NS_ASSERTION(ssle,
-               "passed XML Stylesheet node does not "
-               "implement nsIStyleSheetLinkingElement!");
+    XMLStylesheetProcessingInstruction* aPINode) {
 
   nsresult rv;
 
-  ssle->InitStyleLinkElement(false);
   // We want to be notified when the style sheet finishes loading, so
   // disable style sheet loading for now.
-  ssle->SetEnableUpdates(false);
-  ssle->OverrideBaseURI(mCurrentPrototype->GetURI());
+  aPINode->SetEnableUpdates(false);
+  aPINode->OverrideBaseURI(mCurrentPrototype->GetURI());
 
   rv = aParent->InsertChildBefore(
-      aPINode->AsContent(), aBeforeThis ? aBeforeThis->AsContent() : nullptr,
-      false);
+      aPINode, aBeforeThis ? aBeforeThis->AsContent() : nullptr, false);
   if (NS_FAILED(rv)) return rv;
 
-  ssle->SetEnableUpdates(true);
+  aPINode->SetEnableUpdates(true);
 
   // load the stylesheet if necessary, passing ourselves as
   // nsICSSObserver
-  auto result = ssle->UpdateStyleSheet(this);
+  auto result = aPINode->UpdateStyleSheet(this);
   if (result.isErr()) {
     // Ignore errors from UpdateStyleSheet; we don't want failure to
     // do that to break the XUL document load.  But do propagate out
@@ -455,12 +451,11 @@ nsresult PrototypeDocumentContentSink::ResumeWalkInternal() {
               element->NodeInfo()->Equals(nsGkAtoms::style, kNameSpaceID_SVG)) {
             // XXX sucks that we have to do this -
             // see bug 370111
-            nsCOMPtr<nsIStyleSheetLinkingElement> ssle =
-                do_QueryInterface(element);
-            NS_ASSERTION(ssle,
+            auto* linkStyle = LinkStyle::FromNode(*element);
+            NS_ASSERTION(linkStyle,
                          "<html:style> doesn't implement "
                          "nsIStyleSheetLinkingElement?");
-            Unused << ssle->UpdateStyleSheet(nullptr);
+            Unused << linkStyle->UpdateStyleSheet(nullptr);
           }
         }
         // Now pop the context stack back up to the parent
diff --git a/dom/prototype/PrototypeDocumentContentSink.h b/dom/prototype/PrototypeDocumentContentSink.h
index b69ddf3ce6..b368e169ed 100644
--- a/dom/prototype/PrototypeDocumentContentSink.h
+++ b/dom/prototype/PrototypeDocumentContentSink.h
@@ -34,6 +34,7 @@ namespace dom {
 class Element;
 class ScriptLoader;
 class Document;
+class XMLStylesheetProcessingInstruction;
 }  // namespace dom
 }  // namespace mozilla
 
@@ -236,7 +237,7 @@ class PrototypeDocumentContentSink final : public nsIStreamLoaderObserver,
    */
   nsresult InsertXMLStylesheetPI(const nsXULPrototypePI* aProtoPI,
                                  nsINode* aParent, nsINode* aBeforeThis,
-                                 nsIContent* aPINode);
+                                 XMLStylesheetProcessingInstruction* aPINode);
   void CloseElement(Element* aElement);
 };
 
diff --git a/dom/push/PushManager.cpp b/dom/push/PushManager.cpp
index 7ef5269d12..6bd2811fb5 100644
--- a/dom/push/PushManager.cpp
+++ b/dom/push/PushManager.cpp
@@ -26,6 +26,7 @@
 
 #include "nsComponentManagerUtils.h"
 #include "nsContentUtils.h"
+#include "nsServiceManagerUtils.h"
 
 namespace mozilla {
 namespace dom {
diff --git a/dom/push/test/xpcshell/head-http2.js b/dom/push/test/xpcshell/head-http2.js
index e3b02a012b..5292f975a1 100644
--- a/dom/push/test/xpcshell/head-http2.js
+++ b/dom/push/test/xpcshell/head-http2.js
@@ -13,18 +13,6 @@ function getTestServerPort() {
   return port;
 }
 
-function getTestProxyPort() {
-  let portEnv = Cc["@mozilla.org/process/environment;1"]
-    .getService(Ci.nsIEnvironment)
-    .get("MOZHTTP2_PROXY_PORT");
-  let port = parseInt(portEnv, 10);
-  if (!Number.isFinite(port) || port < 1 || port > 65535) {
-    throw new Error(`Invalid port in MOZHTTP2_PROXY_PORT env var: ${portEnv}`);
-  }
-  info(`Using HTTP/2 proxy on port ${port}`);
-  return port;
-}
-
 function readFile(file) {
   let fstream = Cc["@mozilla.org/network/file-input-stream;1"].createInstance(
     Ci.nsIFileInputStream
diff --git a/dom/quota/ActorsParent.cpp b/dom/quota/ActorsParent.cpp
index db85031286..d61472f406 100644
--- a/dom/quota/ActorsParent.cpp
+++ b/dom/quota/ActorsParent.cpp
@@ -7726,22 +7726,21 @@ auto QuotaManager::GetDirectoryLockTable(PersistenceType aPersistenceType)
 bool QuotaManager::IsSanitizedOriginValid(const nsACString& aSanitizedOrigin) {
   AssertIsOnIOThread();
 
-  bool valid;
-  if (auto entry = mValidOrigins.LookupForAdd(aSanitizedOrigin)) {
-    // We already parsed this sanitized origin string.
-    valid = entry.Data();
-  } else {
-    nsCString spec;
-    OriginAttributes attrs;
-    nsCString originalSuffix;
-    OriginParser::ResultType result = OriginParser::ParseOrigin(
-        aSanitizedOrigin, spec, &attrs, originalSuffix);
+  return mValidOrigins.WithEntryHandle(
+      aSanitizedOrigin, [&aSanitizedOrigin](auto&& entry) {
+        if (entry) {
+          // We already parsed this sanitized origin string.
+          return entry.Data();
+        }
 
-    valid = result == OriginParser::ValidOrigin;
-    entry.OrInsert([valid]() { return valid; });
-  }
+        nsCString spec;
+        OriginAttributes attrs;
+        nsCString originalSuffix;
+        const auto result = OriginParser::ParseOrigin(aSanitizedOrigin, spec,
+                                                      &attrs, originalSuffix);
 
-  return valid;
+        return entry.Insert(result == OriginParser::ValidOrigin);
+      });
 }
 
 int64_t QuotaManager::GenerateDirectoryLockId() {
diff --git a/dom/script/ScriptKind.h b/dom/script/ScriptKind.h
new file mode 100644
index 0000000000..09b52f857d
--- /dev/null
+++ b/dom/script/ScriptKind.h
@@ -0,0 +1,16 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_ScriptKind_h
+#define mozilla_dom_ScriptKind_h
+
+namespace mozilla {
+namespace dom {
+
+enum class ScriptKind { eClassic, eModule, eEvent };
+
+}  // namespace dom
+}  // namespace mozilla
+
+#endif
diff --git a/dom/script/ScriptLoadHandler.cpp b/dom/script/ScriptLoadHandler.cpp
index a76bc53e46..4925cccb3c 100644
--- a/dom/script/ScriptLoadHandler.cpp
+++ b/dom/script/ScriptLoadHandler.cpp
@@ -93,6 +93,14 @@ ScriptLoadHandler::OnIncrementalData(nsIIncrementalStreamLoader* aLoader,
                                      nsISupports* aContext,
                                      uint32_t aDataLength, const uint8_t* aData,
                                      uint32_t* aConsumedLength) {
+  nsCOMPtr<nsIRequest> channelRequest;
+  aLoader->GetRequest(getter_AddRefs(channelRequest));
+
+  if (!mPreloadStartNotified) {
+    mPreloadStartNotified = true;
+    mRequest->NotifyStart(channelRequest);
+  }
+
   if (mRequest->IsCanceled()) {
     // If request cancelled, ignore any incoming data.
     *aConsumedLength = aDataLength;
@@ -144,8 +152,6 @@ ScriptLoadHandler::OnIncrementalData(nsIIncrementalStreamLoader* aLoader,
     *aConsumedLength = aDataLength;
     rv = MaybeDecodeSRI();
     if (NS_FAILED(rv)) {
-      nsCOMPtr<nsIRequest> channelRequest;
-      aLoader->GetRequest(getter_AddRefs(channelRequest));
       return channelRequest->Cancel(mScriptLoader->RestartLoad(mRequest));
     }
   }
@@ -335,6 +341,14 @@ ScriptLoadHandler::OnStreamComplete(nsIIncrementalStreamLoader* aLoader,
   nsCOMPtr<nsIRequest> channelRequest;
   aLoader->GetRequest(getter_AddRefs(channelRequest));
 
+  if (!mPreloadStartNotified) {
+    mPreloadStartNotified = true;
+    mRequest->NotifyStart(channelRequest);
+  }
+
+  auto notifyStop =
+      MakeScopeExit([&] { mRequest->NotifyStop(channelRequest, rv); });
+
   if (!mRequest->IsCanceled()) {
     if (mRequest->IsUnknownDataType()) {
       rv = EnsureKnownDataType(aLoader);
diff --git a/dom/script/ScriptLoadHandler.h b/dom/script/ScriptLoadHandler.h
index 928f830159..ca1328c5cb 100644
--- a/dom/script/ScriptLoadHandler.h
+++ b/dom/script/ScriptLoadHandler.h
@@ -96,6 +96,9 @@ class ScriptLoadHandler final : public nsIIncrementalStreamLoaderObserver {
 
   // Unicode decoder for charset.
   mozilla::UniquePtr<mozilla::Decoder> mDecoder;
+
+  // Flipped to true after calling NotifyStart the first time
+  bool mPreloadStartNotified = false;
 };
 
 }  // namespace dom
diff --git a/dom/script/ScriptLoadRequest.cpp b/dom/script/ScriptLoadRequest.cpp
index 20ff324974..b326f18d64 100644
--- a/dom/script/ScriptLoadRequest.cpp
+++ b/dom/script/ScriptLoadRequest.cpp
@@ -10,6 +10,8 @@
 #include "mozilla/Utf8.h"  // mozilla::Utf8Unit
 
 #include "nsContentUtils.h"
+#include "nsIClassOfService.h"
+#include "nsISupportsPriority.h"
 #include "ScriptLoadRequest.h"
 #include "ScriptSettings.h"
 
@@ -169,8 +171,11 @@ inline ModuleLoadRequest* ScriptLoadRequest::AsModuleRequest() {
   return static_cast<ModuleLoadRequest*>(this);
 }
 
-void ScriptLoadRequest::SetScriptMode(bool aDeferAttr, bool aAsyncAttr) {
-  if (aAsyncAttr) {
+void ScriptLoadRequest::SetScriptMode(bool aDeferAttr, bool aAsyncAttr,
+                                      bool aLinkPreload) {
+  if (aLinkPreload) {
+    mScriptMode = ScriptMode::eLinkPreload;
+  } else if (aAsyncAttr) {
     mScriptMode = ScriptMode::eAsync;
   } else if (aDeferAttr || IsModuleRequest()) {
     mScriptMode = ScriptMode::eDeferred;
@@ -219,6 +224,24 @@ void ScriptLoadRequest::SetScript(JSScript* aScript) {
   HoldJSObjects(this);
 }
 
+// static
+void ScriptLoadRequest::PrioritizeAsPreload(nsIChannel* aChannel) {
+  if (nsCOMPtr<nsIClassOfService> cos = do_QueryInterface(aChannel)) {
+    cos->AddClassFlags(nsIClassOfService::Unblocked);
+  }
+  if (nsCOMPtr<nsISupportsPriority> sp = do_QueryInterface(aChannel)) {
+    sp->AdjustPriority(nsISupportsPriority::PRIORITY_HIGHEST);
+  }
+}
+
+void ScriptLoadRequest::PrioritizeAsPreload() {
+  if (!IsLinkPreloadScript()) {
+    // Do the prioritization only if this request has not already been created
+    // as a preload.
+    PrioritizeAsPreload(Channel());
+  }
+}
+
 //////////////////////////////////////////////////////////////
 // ScriptLoadRequestList
 //////////////////////////////////////////////////////////////
diff --git a/dom/script/ScriptLoadRequest.h b/dom/script/ScriptLoadRequest.h
index 7b9b323254..a2e10b9f0f 100644
--- a/dom/script/ScriptLoadRequest.h
+++ b/dom/script/ScriptLoadRequest.h
@@ -12,12 +12,14 @@
 #include "mozilla/dom/SRIMetadata.h"
 #include "mozilla/LinkedList.h"
 #include "mozilla/Maybe.h"
+#include "mozilla/PreloaderBase.h"
 #include "mozilla/Utf8.h"  // mozilla::Utf8Unit
 #include "mozilla/Variant.h"
 #include "mozilla/Vector.h"
 #include "nsCOMPtr.h"
 #include "nsCycleCollectionParticipant.h"
 #include "nsIScriptElement.h"
+#include "ScriptKind.h"
 
 class nsICacheInfoChannel;
 
@@ -27,8 +29,6 @@ namespace dom {
 class ModuleLoadRequest;
 class ScriptLoadRequestList;
 
-enum class ScriptKind { eClassic, eModule, eEvent };
-
 /*
  * Some options used when fetching script resources. This only loosely
  * corresponds to HTML's "script fetch options".
@@ -60,7 +60,7 @@ class ScriptFetchOptions {
  */
 
 class ScriptLoadRequest
-    : public nsISupports,
+    : public PreloaderBase,
       private mozilla::LinkedListElement<ScriptLoadRequest> {
   typedef LinkedListElement<ScriptLoadRequest> super;
 
@@ -79,6 +79,10 @@ class ScriptLoadRequest
   NS_DECL_CYCLE_COLLECTING_ISUPPORTS
   NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(ScriptLoadRequest)
 
+  // PreloaderBase
+  static void PrioritizeAsPreload(nsIChannel* aChannel);
+  virtual void PrioritizeAsPreload() override;
+
   bool IsModuleRequest() const { return mKind == ScriptKind::eModule; }
 
   ModuleLoadRequest* AsModuleRequest();
@@ -220,9 +224,19 @@ class ScriptLoadRequest
                          : ScriptText<Utf8Unit>().clearAndFree();
   }
 
-  enum class ScriptMode : uint8_t { eBlocking, eDeferred, eAsync };
+  enum class ScriptMode : uint8_t {
+    eBlocking,
+    eDeferred,
+    eAsync,
+    eLinkPreload  // this is a load initiated by <link rel="preload"
+                  // as="script"> tag
+  };
 
-  void SetScriptMode(bool aDeferAttr, bool aAsyncAttr);
+  void SetScriptMode(bool aDeferAttr, bool aAsyncAttr, bool aLinkPreload);
+
+  bool IsLinkPreloadScript() const {
+    return mScriptMode == ScriptMode::eLinkPreload;
+  }
 
   bool IsBlockingScript() const { return mScriptMode == ScriptMode::eBlocking; }
 
diff --git a/dom/script/ScriptLoader.cpp b/dom/script/ScriptLoader.cpp
index 7131773dad..00dff357fc 100644
--- a/dom/script/ScriptLoader.cpp
+++ b/dom/script/ScriptLoader.cpp
@@ -47,6 +47,7 @@
 #include "nsICacheInfoChannel.h"
 #include "nsITimedChannel.h"
 #include "nsIScriptElement.h"
+#include "nsISupportsPriority.h"
 #include "nsIDocShell.h"
 #include "nsContentUtils.h"
 #include "nsUnicharUtils.h"
@@ -1277,6 +1278,9 @@ nsresult ScriptLoader::RestartLoad(ScriptLoadRequest* aRequest) {
   aRequest->mScriptBytecode.clearAndFree();
   TRACE_FOR_TEST(aRequest->GetScriptElement(), "scriptloader_fallback");
 
+  // Notify preload restart so that we can register this preload request again.
+  aRequest->NotifyRestart(mDocument);
+
   // Start a new channel from which we explicitly request to stream the source
   // instead of the bytecode.
   aRequest->mProgress = ScriptLoadRequest::Progress::eLoading_Source;
@@ -1423,8 +1427,16 @@ nsresult ScriptLoader::StartLoad(ScriptLoadRequest* aRequest) {
   LOG(("ScriptLoadRequest (%p): mode=%u tracking=%d", aRequest,
        unsigned(aRequest->mScriptMode), aRequest->IsTracking()));
 
-  nsCOMPtr<nsIClassOfService> cos(do_QueryInterface(channel));
-  if (cos) {
+  if (aRequest->IsLinkPreloadScript()) {
+    // This is <link rel="preload" as="script"> initiated speculative load,
+    // put it to the group that is not blocked by leaders and doesn't block
+    // follower at the same time. Giving it a much higher priority will make
+    // this request be processed ahead of other Unblocked requests, but with
+    // the same weight as Leaders.  This will make us behave similar way for
+    // both http2 and http1.
+    ScriptLoadRequest::PrioritizeAsPreload(channel);
+    ScriptLoadRequest::AddLoadBackgroundFlag(channel);
+  } else if (nsCOMPtr<nsIClassOfService> cos = do_QueryInterface(channel)) {
     if (aRequest->mScriptFromHead && aRequest->IsBlockingScript()) {
       // synchronous head scripts block loading of most other non js/css
       // content such as images, Leader implicitely disallows tailing
@@ -1489,7 +1501,11 @@ nsresult ScriptLoader::StartLoad(ScriptLoadRequest* aRequest) {
   // Set the initiator type
   nsCOMPtr<nsITimedChannel> timedChannel(do_QueryInterface(httpChannel));
   if (timedChannel) {
-    timedChannel->SetInitiatorType(NS_LITERAL_STRING("script"));
+    if (aRequest->IsLinkPreloadScript()) {
+      timedChannel->SetInitiatorType(NS_LITERAL_STRING("link"));
+    } else {
+      timedChannel->SetInitiatorType(NS_LITERAL_STRING("script"));
+    }
   }
 
   UniquePtr<mozilla::dom::SRICheckDataVerifier> sriDataVerifier;
@@ -1509,7 +1525,21 @@ nsresult ScriptLoader::StartLoad(ScriptLoadRequest* aRequest) {
   rv = NS_NewIncrementalStreamLoader(getter_AddRefs(loader), handler);
   NS_ENSURE_SUCCESS(rv, rv);
 
+  auto key = PreloadHashKey::CreateAsScript(
+      aRequest->mURI, aRequest->CORSMode(), aRequest->mKind,
+      aRequest->ReferrerPolicy());
+  aRequest->NotifyOpen(&key, channel, mDocument,
+                       aRequest->IsLinkPreloadScript());
+
   rv = channel->AsyncOpen(loader);
+
+  if (NS_FAILED(rv)) {
+    // Make sure to inform any <link preload> tags about failure to load the
+    // resource.
+    aRequest->NotifyStart(channel);
+    aRequest->NotifyStop(rv);
+  }
+
   NS_ENSURE_SUCCESS(rv, rv);
 
   if (aRequest->IsModuleRequest()) {
@@ -1691,7 +1721,7 @@ bool ScriptLoader::ProcessExternalScript(nsIScriptElement* aElement,
     // It's possible these attributes changed since we started the preload so
     // update them here.
     request->SetScriptMode(aElement->GetScriptDeferred(),
-                           aElement->GetScriptAsync());
+                           aElement->GetScriptAsync(), false);
 
     AccumulateCategorical(LABELS_DOM_SCRIPT_PRELOAD_RESULT::Used);
   } else {
@@ -1710,7 +1740,7 @@ bool ScriptLoader::ProcessExternalScript(nsIScriptElement* aElement,
                                 ourCORSMode, sriMetadata, referrerPolicy);
     request->mIsInline = false;
     request->SetScriptMode(aElement->GetScriptDeferred(),
-                           aElement->GetScriptAsync());
+                           aElement->GetScriptAsync(), false);
     // keep request->mScriptFromHead to false so we don't treat non preloaded
     // scripts as blockers for full page load. See bug 792438.
 
@@ -1860,7 +1890,7 @@ bool ScriptLoader::ProcessInlineScript(nsIScriptElement* aElement,
   // inline classic scripts ignore both these attributes.
   MOZ_ASSERT(!aElement->GetScriptDeferred());
   MOZ_ASSERT_IF(!request->IsModuleRequest(), !aElement->GetScriptAsync());
-  request->SetScriptMode(false, aElement->GetScriptAsync());
+  request->SetScriptMode(false, aElement->GetScriptAsync(), false);
 
   LOG(("ScriptLoadRequest (%p): Created request for inline script",
        request.get()));
@@ -1975,6 +2005,14 @@ ScriptLoadRequest* ScriptLoader::LookupPreloadRequest(
   // Report any errors that we skipped while preloading.
   ReportPreloadErrorsToConsole(request);
 
+  // This makes sure the pending preload (if exists) for this resource is
+  // properly marked as used and thus not notified in the console as unused.
+  request->NotifyUsage();
+  // A used preload must no longer be found in the Document's hash table.  Any
+  // <link preload> tag after the <script> tag will start a new request, that
+  // can be satisfied from a different cache, but not from the preload cache.
+  request->RemoveSelf(mDocument);
+
   return request;
 }
 
@@ -3901,6 +3939,7 @@ void ScriptLoader::PreloadURI(nsIURI* aURI, const nsAString& aCharset,
                               const nsAString& aCrossOrigin,
                               const nsAString& aIntegrity, bool aScriptFromHead,
                               bool aAsync, bool aDefer, bool aNoModule,
+                              bool aLinkPreload,
                               const ReferrerPolicy aReferrerPolicy) {
   NS_ENSURE_TRUE_VOID(mDocument);
   // Check to see if scripts has been turned off.
@@ -3939,7 +3978,7 @@ void ScriptLoader::PreloadURI(nsIURI* aURI, const nsAString& aCharset,
       Element::StringToCORSMode(aCrossOrigin), sriMetadata, aReferrerPolicy);
   request->mIsInline = false;
   request->mScriptFromHead = aScriptFromHead;
-  request->SetScriptMode(aDefer, aAsync);
+  request->SetScriptMode(aDefer, aAsync, aLinkPreload);
   request->SetIsPreloadRequest();
 
   if (LOG_ENABLED()) {
diff --git a/dom/script/ScriptLoader.h b/dom/script/ScriptLoader.h
index d378e9e14d..0ea4f80266 100644
--- a/dom/script/ScriptLoader.h
+++ b/dom/script/ScriptLoader.h
@@ -23,6 +23,7 @@
 #include "mozilla/MozPromise.h"
 #include "mozilla/Utf8.h"  // mozilla::Utf8Unit
 #include "mozilla/Vector.h"
+#include "ScriptKind.h"
 
 class nsIURI;
 
@@ -338,6 +339,7 @@ class ScriptLoader final : public nsISupports {
                           const nsAString& aType, const nsAString& aCrossOrigin,
                           const nsAString& aIntegrity, bool aScriptFromHead,
                           bool aAsync, bool aDefer, bool aNoModule,
+                          bool aLinkPreload,
                           const ReferrerPolicy aReferrerPolicy);
 
   /**
diff --git a/dom/script/moz.build b/dom/script/moz.build
index 775639f96a..369f943bce 100644
--- a/dom/script/moz.build
+++ b/dom/script/moz.build
@@ -19,6 +19,7 @@ EXPORTS.mozilla.dom += [
     'LoadedScript.h',
     'ScriptDecoding.h',
     'ScriptElement.h',
+    'ScriptKind.h',
     'ScriptLoader.h',
     'ScriptLoadRequest.h',
     'ScriptSettings.h',
diff --git a/dom/security/CSPEvalChecker.cpp b/dom/security/CSPEvalChecker.cpp
index 6fd242e947..0084d088b3 100644
--- a/dom/security/CSPEvalChecker.cpp
+++ b/dom/security/CSPEvalChecker.cpp
@@ -35,8 +35,8 @@ nsresult CheckInternal(nsIContentSecurityPolicy* aCSP,
 
 #if !defined(ANDROID)
   JSContext* cx = nsContentUtils::GetCurrentJSContext();
-  if (!nsContentSecurityUtils::IsEvalAllowed(cx, aSubjectPrincipal,
-                                             aExpression)) {
+  if (cx && !nsContentSecurityUtils::IsEvalAllowed(cx, aSubjectPrincipal,
+                                                    aExpression)) {
     *aAllowed = false;
     return NS_OK;
   }
diff --git a/dom/security/nsCSPParser.cpp b/dom/security/nsCSPParser.cpp
index 4f550c6548..393c9ba984 100644
--- a/dom/security/nsCSPParser.cpp
+++ b/dom/security/nsCSPParser.cpp
@@ -892,14 +892,11 @@ nsCSPDirective* nsCSPParser::directiveName() {
     return new nsUpgradeInsecureDirective(CSP_StringToCSPDirective(mCurToken));
   }
 
-  // child-src by itself is deprecatd but will be enforced
-  //   * for workers (if worker-src is not explicitly specified)
-  //   * for frames  (if frame-src is not explicitly specified)
+  // if we have a child-src, cache it as a fallback for
+  //   * workers (if worker-src is not explicitly specified)
+  //   * frames  (if frame-src is not explicitly specified)
   if (CSP_IsDirective(mCurToken,
                       nsIContentSecurityPolicy::CHILD_SRC_DIRECTIVE)) {
-    AutoTArray<nsString, 1> params = {mCurToken};
-    logWarningErrorToConsole(nsIScriptError::warningFlag,
-                             "deprecatedChildSrcDirective", params);
     mChildSrc = new nsCSPChildSrcDirective(CSP_StringToCSPDirective(mCurToken));
     return mChildSrc;
   }
diff --git a/dom/security/nsCSPService.cpp b/dom/security/nsCSPService.cpp
index b7c2741fc9..b219a08b74 100644
--- a/dom/security/nsCSPService.cpp
+++ b/dom/security/nsCSPService.cpp
@@ -104,7 +104,7 @@ bool subjectToCSP(nsIURI* aURI, nsContentPolicyType aContentType) {
   uint32_t contentType = aLoadInfo->InternalContentPolicyType();
   nsCOMPtr<nsISupports> requestContext = aLoadInfo->GetLoadingContext();
   nsCOMPtr<nsIURI> requestOrigin;
-  nsCOMPtr<nsIPrincipal> loadingPrincipal = aLoadInfo->LoadingPrincipal();
+  nsCOMPtr<nsIPrincipal> loadingPrincipal = aLoadInfo->GetLoadingPrincipal();
   if (loadingPrincipal) {
     loadingPrincipal->GetURI(getter_AddRefs(requestOrigin));
   }
diff --git a/dom/security/nsCSPUtils.cpp b/dom/security/nsCSPUtils.cpp
index 9533ea485a..555a1b63bd 100644
--- a/dom/security/nsCSPUtils.cpp
+++ b/dom/security/nsCSPUtils.cpp
@@ -262,12 +262,15 @@ CSPDirective CSP_ContentTypeToDirective(nsContentPolicyType aType) {
     case nsIContentPolicy::TYPE_INTERNAL_MODULE:
     case nsIContentPolicy::TYPE_INTERNAL_MODULE_PRELOAD:
     case nsIContentPolicy::TYPE_INTERNAL_WORKER_IMPORT_SCRIPTS:
+    case nsIContentPolicy::TYPE_INTERNAL_AUDIOWORKLET:
+    case nsIContentPolicy::TYPE_INTERNAL_PAINTWORKLET:
       return nsIContentSecurityPolicy::SCRIPT_SRC_DIRECTIVE;
 
     case nsIContentPolicy::TYPE_STYLESHEET:
       return nsIContentSecurityPolicy::STYLE_SRC_DIRECTIVE;
 
     case nsIContentPolicy::TYPE_FONT:
+    case nsIContentPolicy::TYPE_INTERNAL_FONT_PRELOAD:
       return nsIContentSecurityPolicy::FONT_SRC_DIRECTIVE;
 
     case nsIContentPolicy::TYPE_MEDIA:
@@ -875,6 +878,25 @@ bool nsCSPNonceSrc::permits(nsIURI* aUri, const nsAString& aNonce,
                  NS_ConvertUTF16toUTF8(aNonce).get()));
   }
 
+  if (aReportOnly && aWasRedirected && aNonce.IsEmpty()) {
+    /* Fix for Bug 1505412
+     *  If we land here, we're currently handling a script-preload which got
+     *  redirected. Preloads do not have any info about the nonce assiociated.
+     *  Because of Report-Only the preload passes the 1st CSP-check so the
+     *  preload does not get retried with a nonce attached.
+     *  Currently we're relying on the script-manager to
+     *  provide a fake loadinfo to check the preloads against csp.
+     *  So during HTTPChannel->OnRedirect we cant check csp for this case.
+     *  But as the script-manager already checked the csp,
+     *  a report would already have been send,
+     *  if the nonce didnt match.
+     *  So we can pass the check here for Report-Only Cases.
+     */
+    MOZ_ASSERT(aParserCreated == false,
+               "Skipping nonce-check is only allowed for Preloads");
+    return true;
+  }
+
   // nonces can not be invalidated by strict-dynamic
   return mNonce.Equals(aNonce);
 }
diff --git a/dom/security/nsContentSecurityManager.cpp b/dom/security/nsContentSecurityManager.cpp
index c5a1f1790b..884f627f85 100644
--- a/dom/security/nsContentSecurityManager.cpp
+++ b/dom/security/nsContentSecurityManager.cpp
@@ -283,11 +283,11 @@ static nsresult DoCheckLoadURIChecks(nsIURI* aURI, nsILoadInfo* aLoadInfo) {
       nsIContentPolicy::TYPE_INTERNAL_DTD) {
     RefPtr<Document> doc;
     aLoadInfo->GetLoadingDocument(getter_AddRefs(doc));
-    return nsContentUtils::PrincipalAllowsL10n(
-               aLoadInfo->TriggeringPrincipal(),
-               doc ? doc->GetDocumentURI() : nullptr)
-               ? NS_OK
-               : NS_ERROR_DOM_BAD_URI;
+    bool allowed = false;
+    aLoadInfo->TriggeringPrincipal()->IsL10nAllowed(
+        doc ? doc->GetDocumentURI() : nullptr, &allowed);
+
+    return allowed ? NS_OK : NS_ERROR_DOM_BAD_URI;
   }
 
   // This is used in order to allow a privileged DOMParser to parse documents
@@ -334,7 +334,11 @@ static nsresult DoSOPChecks(nsIURI* aURI, nsILoadInfo* aLoadInfo,
     return DoCheckLoadURIChecks(aURI, aLoadInfo);
   }
 
-  NS_ENSURE_FALSE(NS_HasBeenCrossOrigin(aChannel, true), NS_ERROR_DOM_BAD_URI);
+  if (NS_HasBeenCrossOrigin(aChannel, true)) {
+    NS_SetRequestBlockingReason(aLoadInfo,
+                                nsILoadInfo::BLOCKING_REASON_NOT_SAME_ORIGIN);
+    return NS_ERROR_DOM_BAD_URI;
+  }
 
   return NS_OK;
 }
@@ -711,7 +715,7 @@ static void DebugDoContentSecurityCheck(nsIChannel* aChannel,
 
     // Log Principals
     nsCOMPtr<nsIPrincipal> requestPrincipal = aLoadInfo->TriggeringPrincipal();
-    LogPrincipal(aLoadInfo->LoadingPrincipal(),
+    LogPrincipal(aLoadInfo->GetLoadingPrincipal(),
                  NS_LITERAL_STRING("loadingPrincipal"));
     LogPrincipal(requestPrincipal, NS_LITERAL_STRING("triggeringPrincipal"));
     LogPrincipal(aLoadInfo->PrincipalToInherit(),
@@ -769,8 +773,8 @@ nsresult nsContentSecurityManager::CheckAllowLoadInSystemPrivilegedContext(
 
   // nothing to do here if we are not loading a resource into a
   // system prvileged context.
-  if (!loadInfo->LoadingPrincipal() ||
-      !loadInfo->LoadingPrincipal()->IsSystemPrincipal()) {
+  if (!loadInfo->GetLoadingPrincipal() ||
+      !loadInfo->GetLoadingPrincipal()->IsSystemPrincipal()) {
     return NS_OK;
   }
 
@@ -970,7 +974,7 @@ nsresult nsContentSecurityManager::CheckChannel(nsIChannel* aChannel) {
     // We shouldn't have the SEC_COOKIES_SAME_ORIGIN flag for top level loads
     MOZ_ASSERT(loadInfo->GetExternalContentPolicyType() !=
                nsIContentPolicy::TYPE_DOCUMENT);
-    nsIPrincipal* loadingPrincipal = loadInfo->LoadingPrincipal();
+    nsIPrincipal* loadingPrincipal = loadInfo->GetLoadingPrincipal();
 
     // It doesn't matter what we pass for the third, data-inherits, argument.
     // Any protocol which inherits won't pay attention to cookies anyway.
diff --git a/dom/security/nsMixedContentBlocker.cpp b/dom/security/nsMixedContentBlocker.cpp
index 3b8e94345e..765033d001 100644
--- a/dom/security/nsMixedContentBlocker.cpp
+++ b/dom/security/nsMixedContentBlocker.cpp
@@ -270,7 +270,7 @@ nsMixedContentBlocker::AsyncOnChannelRedirect(
 
   // Get the loading Info from the old channel
   nsCOMPtr<nsILoadInfo> loadInfo = aOldChannel->LoadInfo();
-  nsCOMPtr<nsIPrincipal> requestingPrincipal = loadInfo->LoadingPrincipal();
+  nsCOMPtr<nsIPrincipal> requestingPrincipal = loadInfo->GetLoadingPrincipal();
 
   // Since we are calling shouldLoad() directly on redirects, we don't go
   // through the code in nsContentPolicyUtils::NS_CheckContentLoadPolicy().
@@ -316,9 +316,13 @@ nsMixedContentBlocker::ShouldLoad(nsIURI* aContentLocation,
   nsCOMPtr<nsISupports> requestingContext = aLoadInfo->GetLoadingContext();
   nsCOMPtr<nsIPrincipal> requestPrincipal = aLoadInfo->TriggeringPrincipal();
   nsCOMPtr<nsIURI> requestingLocation;
-  nsCOMPtr<nsIPrincipal> loadingPrincipal = aLoadInfo->LoadingPrincipal();
-  if (loadingPrincipal) {
-    loadingPrincipal->GetURI(getter_AddRefs(requestingLocation));
+  nsCOMPtr<nsIPrincipal> loadingPrincipal = aLoadInfo->GetLoadingPrincipal();
+
+  // We need to get a Requesting Location if possible
+  // so we're casting to BasePrincipal to acess GetURI
+  auto* basePrin = BasePrincipal::Cast(loadingPrincipal);
+  if (basePrin) {
+    basePrin->GetURI(getter_AddRefs(requestingLocation));
   }
 
   // We pass in false as the first parameter to ShouldLoad(), because the
@@ -669,8 +673,11 @@ nsresult nsMixedContentBlocker::ShouldLoad(
   }
 
   nsCOMPtr<nsIURI> requestingLocation;
-  if (principal) {
-    principal->GetURI(getter_AddRefs(requestingLocation));
+  // We need to get a Requesting Location if possible
+  // so we're casting to BasePrincipal to acess GetURI
+  auto* basePrin = BasePrincipal::Cast(principal);
+  if (basePrin) {
+    basePrin->GetURI(getter_AddRefs(requestingLocation));
   }
 
   // 2) if aRequestingContext yields a principal but no location, we check if
diff --git a/dom/security/test/csp/file_bug1505412.sjs b/dom/security/test/csp/file_bug1505412.sjs
new file mode 100644
index 0000000000..dc7fa48b62
--- /dev/null
+++ b/dom/security/test/csp/file_bug1505412.sjs
@@ -0,0 +1,36 @@
+// https://bugzilla.mozilla.org/show_bug.cgi?id=650386
+// This SJS file serves file_redirect_content.html
+// with a CSP that will trigger a violation and that will report it
+// to file_redirect_report.sjs
+//
+// This handles 301, 302, 303 and 307 redirects. The HTTP status code
+// returned/type of redirect to do comes from the query string
+// parameter passed in from the test_bug650386_* files and then also
+// uses that value in the report-uri parameter of the CSP
+function handleRequest(request, response) {
+  response.setHeader("Cache-Control", "no-cache", false);
+
+  // this gets used in the CSP as part of the report URI.
+  var redirect = request.queryString;
+
+  if (!redirect) {
+    // if we somehow got some bogus redirect code here,
+    // do a 302 redirect to the same URL as the report URI
+    // redirects to - this will fail the test.
+    var loc =
+      "http://sub1.test1.example.org/tests/dom/security/test/csp/file_bug1505412.sjs?redirected";
+    response.setStatusLine("1.1", 302, "Found");
+    response.setHeader("Location", loc, false);
+    return;
+  }
+
+  // response.setHeader("content-type", "text/application", false);
+  // the actual file content.
+  // this image load will (intentionally) fail due to the CSP policy of default-src: 'self'
+  // specified by the CSP string above.
+  var content = "info('Script Loaded')";
+
+  response.write(content);
+
+  return;
+}
diff --git a/dom/security/test/csp/file_bug1505412_frame.html b/dom/security/test/csp/file_bug1505412_frame.html
new file mode 100644
index 0000000000..b8ff33b4b4
--- /dev/null
+++ b/dom/security/test/csp/file_bug1505412_frame.html
@@ -0,0 +1,14 @@
+<!DOCTYPE HTML>
+<html>
+
+<head>
+    <title> Bug 1505412 CSP-RO reports violations in inline-scripts with nonce</title>
+    <script src="/tests/SimpleTest/SimpleTest.js" nonce="foobar"></script>
+    <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+
+
+<body>
+    <script src="file_bug1505412.sjs" nonce="foobar"></script>
+</body>
+
+</html>
diff --git a/dom/security/test/csp/file_bug1505412_frame.html^headers^ b/dom/security/test/csp/file_bug1505412_frame.html^headers^
new file mode 100644
index 0000000000..e60b63c29c
--- /dev/null
+++ b/dom/security/test/csp/file_bug1505412_frame.html^headers^
@@ -0,0 +1 @@
+Content-Security-Policy-Report-Only: script-src 'nonce-foobar'; report-uri file_bug1505412_reporter.sjs
diff --git a/dom/security/test/csp/file_bug1505412_reporter.sjs b/dom/security/test/csp/file_bug1505412_reporter.sjs
new file mode 100644
index 0000000000..323a4edb1c
--- /dev/null
+++ b/dom/security/test/csp/file_bug1505412_reporter.sjs
@@ -0,0 +1,18 @@
+function handleRequest(request, response) {
+  var receivedRequests = parseInt(getState("requests"));
+  if (isNaN(receivedRequests)) {
+    receivedRequests = 0;
+  }
+  if (request.queryString.includes("state")) {
+    response.write(receivedRequests);
+    return;
+  }
+  if (request.queryString.includes("flush")) {
+    setState("requests", "0");
+    response.write("OK");
+    return;
+  }
+  receivedRequests = receivedRequests + 1;
+  setState("requests", "" + receivedRequests);
+  response.write("OK");
+}
diff --git a/dom/security/test/csp/file_link_rel_preload.html b/dom/security/test/csp/file_link_rel_preload.html
new file mode 100644
index 0000000000..1ca3039601
--- /dev/null
+++ b/dom/security/test/csp/file_link_rel_preload.html
@@ -0,0 +1,17 @@
+<!doctype html>
+<html>
+<head>
+  <title>Bug 1599791 - Test link rel=preload</title>
+  <!-- Please note that fakeServer does not exist in our testsuite -->
+  <meta http-equiv="Content-Security-Policy" content="default-src 'none'">
+  <link rel="preload" as="script" href="fakeServer?script"></link>
+  <link rel="preload" as="style" href="fakeServer?style"></link>
+  <link rel="preload" as="image" href="fakeServer?image"></link>
+
+  <link rel="stylesheet" href="fakeServer?style">
+</head>
+<body>
+<script src="fakeServer?script"></script>
+<img src="fakeServer?image"></img>
+</body>
+</html>
diff --git a/dom/security/test/csp/file_object_inherit.html b/dom/security/test/csp/file_object_inherit.html
new file mode 100644
index 0000000000..76c9764162
--- /dev/null
+++ b/dom/security/test/csp/file_object_inherit.html
@@ -0,0 +1,21 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Bug 1457100: Test OBJECT inherits CSP if needed</title>
+  <meta charset="utf-8">
+  <meta http-equiv="Content-Security-Policy" content= "img-src https://bug1457100.test.com"/>
+</head>
+<body>
+<object id="dataObject" data="data:text/html,object<script>var foo = 0;</script>"></object>
+
+<script type="application/javascript">
+  var dataObject = document.getElementById("dataObject");
+  dataObject.onload = function () {
+    var contentDoc = SpecialPowers.wrap(dataObject).contentDocument;
+    var cspJSON = contentDoc.cspJSON;
+    window.parent.postMessage({cspJSON}, "*");
+  }
+</script>
+
+</body>
+</html>
diff --git a/dom/security/test/csp/mochitest.ini b/dom/security/test/csp/mochitest.ini
index fd1da77a07..173a682682 100644
--- a/dom/security/test/csp/mochitest.ini
+++ b/dom/security/test/csp/mochitest.ini
@@ -87,6 +87,10 @@ support-files =
   file_bug1312272.js
   file_bug1312272.html^headers^
   file_bug1452037.html
+  file_bug1505412.sjs
+  file_bug1505412_reporter.sjs
+  file_bug1505412_frame.html
+  file_bug1505412_frame.html^headers^
   file_policyuri_regression_from_multipolicy.html
   file_policyuri_regression_from_multipolicy.html^headers^
   file_policyuri_regression_from_multipolicy_policy
@@ -246,6 +250,8 @@ prefs =
 [test_bug802872.html]
 [test_bug885433.html]
 [test_bug888172.html]
+[test_bug1505412.html]
+skip-if = !debug
 [test_evalscript.html]
 [test_evalscript_blocked_by_strict_dynamic.html]
 [test_evalscript_allowed_by_strict_dynamic.html]
@@ -392,3 +398,9 @@ support-files =
   file_xslt_inherits_csp.xml
   file_xslt_inherits_csp.xml^headers^
   file_xslt_inherits_csp.xsl
+[test_object_inherit.html]
+support-files =
+  file_object_inherit.html
+[test_link_rel_preload.html]
+support-files =
+  file_link_rel_preload.html
diff --git a/dom/security/test/csp/test_bug1505412.html b/dom/security/test/csp/test_bug1505412.html
new file mode 100644
index 0000000000..a350222202
--- /dev/null
+++ b/dom/security/test/csp/test_bug1505412.html
@@ -0,0 +1,50 @@
+<!DOCTYPE HTML>
+<html>
+
+<head>
+    <title> Bug 1505412 CSP-RO reports violations in inline-scripts with nonce</title>
+    <script src="/tests/SimpleTest/SimpleTest.js" nonce="foobar"></script>
+    <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+
+
+<body>
+    <p id="display"></p>
+    <div id="content" style="display: none">
+    </div>
+
+    <a href="https://bugzilla.mozilla.org/show_bug.cgi?id=1505412">Test for 1505412 </a>
+    <script class="testbody" type="text/javascript" nonce="foobar">
+        /* Description of the test:
+            1:  We setup a Proxy that will cause the Test to Fail
+                if Firefox sends a CSP-Report to /report
+            2:  We Load an iframe with has a Script pointing to
+                file_bug1505412.sjs
+            3:  The Preloader will fetch the file and Gets redirected
+            4:  If correct, the File should be loaded and no CSP-Report
+                should be send.
+        */
+
+
+
+        SimpleTest.waitForExplicitFinish();
+        SimpleTest.requestCompleteLog();
+        SimpleTest.requestLongerTimeout(2); // Or might fail for Linux-Debug in some cases.
+        var script;
+
+       window.addEventListener("load",()=>{
+        let t = document.querySelector("#target");
+        t.src = "file_bug1505412_frame.html";
+        t.addEventListener("load",async  () => {
+            let reportCount = await fetch("file_bug1505412_reporter.sjs?state").then(r => r.text());
+            info(reportCount);
+            ok(reportCount == 0 , "Script Loaded without CSP beeing triggered");
+            await fetch("file_bug1505412_reporter.sjs?flush");
+            SimpleTest.finish();
+        });
+       })
+
+    </script>
+    <iframe id="target" frameborder="0"></iframe>
+</body>
+
+</html>
\ No newline at end of file
diff --git a/dom/security/test/csp/test_link_rel_preload.html b/dom/security/test/csp/test_link_rel_preload.html
new file mode 100644
index 0000000000..aaa1916b2f
--- /dev/null
+++ b/dom/security/test/csp/test_link_rel_preload.html
@@ -0,0 +1,77 @@
+<!doctype html>
+<html>
+<head>
+  <title>Bug 1599791 - Test link rel=preload</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<iframe id=testframe></iframe>
+<script class="testbody" type="text/javascript">
+
+// Please note that 'fakeServer' does not exist because the test relies
+// on "csp-on-violate-policy" , and "specialpowers-http-notify-request"
+// which fire if either the request is blocked or fires. The test does
+// not rely on the result of the load.
+
+let TOTAL_TESTS = 3; // script, style, image
+let seenTests = 0;
+
+function examiner() {
+  SpecialPowers.addObserver(this, "csp-on-violate-policy");
+  SpecialPowers.addObserver(this, "specialpowers-http-notify-request");
+}
+examiner.prototype  = {
+  observe(subject, topic, data) {
+    if (topic === "csp-on-violate-policy") {
+      let asciiSpec = SpecialPowers.getPrivilegedProps(
+                       SpecialPowers.do_QueryInterface(subject, "nsIURI"),
+                       "asciiSpec");
+
+      if (asciiSpec.includes("fakeServer?script") ||
+          asciiSpec.includes("fakeServer?style") ||
+          asciiSpec.includes("fakeServer?image")) {
+        let type = asciiSpec.substring(asciiSpec.indexOf("?") + 1);
+        ok (true, type + " should be blocked by CSP");
+        checkFinished();
+      }
+    }
+
+    if (topic === "specialpowers-http-notify-request") {
+      if (data.includes("fakeServer?script") ||
+          data.includes("fakeServer?style") ||
+          data.includes("fakeServer?image")) {
+        let type = data.substring(data.indexOf("?") + 1);
+        ok (false, type + " should not be loaded");
+        checkFinished();
+      }
+    }
+  },
+  remove() {
+    SpecialPowers.removeObserver(this, "csp-on-violate-policy");
+    SpecialPowers.removeObserver(this, "specialpowers-http-notify-request");
+  }
+}
+
+window.examiner = new examiner();
+
+function checkFinished() {
+  seenTests++;
+  if (seenTests == TOTAL_TESTS) {
+    window.examiner.remove();
+    SimpleTest.finish();
+    return;
+  }
+}
+
+SimpleTest.waitForExplicitFinish();
+
+SpecialPowers.pushPrefEnv(
+  {'set':[["network.preload", true]]},
+  function() {
+    document.getElementById("testframe").src = "file_link_rel_preload.html";
+  });
+
+</script>
+</body>
+</html>
diff --git a/dom/security/test/csp/test_object_inherit.html b/dom/security/test/csp/test_object_inherit.html
new file mode 100644
index 0000000000..0d563bde3f
--- /dev/null
+++ b/dom/security/test/csp/test_object_inherit.html
@@ -0,0 +1,30 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Bug 1457100: Test OBJECT inherits CSP if needed</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<iframe style="width:100%;" id="testframe"></iframe>
+
+<script class="testbody" type="text/javascript">
+
+SimpleTest.waitForExplicitFinish();
+
+window.addEventListener("message", receiveMessage);
+function receiveMessage(event) {
+  window.removeEventListener("message", receiveMessage);
+
+  var cspJSON = event.data.cspJSON;
+  ok(cspJSON.includes("img-src"), "found img-src directive");
+  ok(cspJSON.includes("https://bug1457100.test.com"), "found img-src value");
+
+  SimpleTest.finish();
+}
+
+document.getElementById("testframe").src = "file_object_inherit.html";
+
+</script>
+</body>
+</html>
diff --git a/dom/smil/SMILAnimationFunction.cpp b/dom/smil/SMILAnimationFunction.cpp
index b2047e29b7..de0a7ed005 100644
--- a/dom/smil/SMILAnimationFunction.cpp
+++ b/dom/smil/SMILAnimationFunction.cpp
@@ -6,7 +6,7 @@
 
 #include "mozilla/dom/SVGAnimationElement.h"
 #include "mozilla/DebugOnly.h"
-#include "mozilla/Move.h"
+#include <utility>
 #include "mozilla/SMILAttr.h"
 #include "mozilla/SMILCSSValueType.h"
 #include "mozilla/SMILNullType.h"
diff --git a/dom/smil/SMILCSSProperty.cpp b/dom/smil/SMILCSSProperty.cpp
index 57cdb735f6..b87e9ce411 100644
--- a/dom/smil/SMILCSSProperty.cpp
+++ b/dom/smil/SMILCSSProperty.cpp
@@ -7,7 +7,7 @@
 #include "SMILCSSProperty.h"
 
 #include "mozilla/dom/Element.h"
-#include "mozilla/Move.h"
+#include <utility>
 #include "mozilla/ServoBindings.h"
 #include "mozilla/SMILCSSValueType.h"
 #include "mozilla/SMILValue.h"
@@ -53,7 +53,7 @@ SMILValue SMILCSSProperty::GetBaseValue() const {
     // In any case, just return a dummy value (initialized with the right
     // type, so as not to indicate failure).
     SMILValue tmpVal(&SMILCSSValueType::sSingleton);
-    Swap(baseValue, tmpVal);
+    std::swap(baseValue, tmpVal);
     return baseValue;
   }
 
diff --git a/dom/svg/SVGAnimatedNumberList.cpp b/dom/svg/SVGAnimatedNumberList.cpp
index a02d5a98ae..6b1e8c2962 100644
--- a/dom/svg/SVGAnimatedNumberList.cpp
+++ b/dom/svg/SVGAnimatedNumberList.cpp
@@ -142,7 +142,7 @@ SMILValue SVGAnimatedNumberList::SMILAnimatedNumberList::GetBaseValue() const {
   nsresult rv = nlai->CopyFrom(mVal->mBaseVal);
   if (NS_SUCCEEDED(rv)) {
     nlai->SetInfo(mElement);
-    Swap(val, tmp);
+    std::swap(val, tmp);
   }
   return val;
 }
diff --git a/dom/svg/SVGAnimatedPointList.cpp b/dom/svg/SVGAnimatedPointList.cpp
index 14c62c913a..49ace783df 100644
--- a/dom/svg/SVGAnimatedPointList.cpp
+++ b/dom/svg/SVGAnimatedPointList.cpp
@@ -167,7 +167,7 @@ SMILValue SVGAnimatedPointList::SMILAnimatedPointList::GetBaseValue() const {
   nsresult rv = list->CopyFrom(mVal->mBaseVal);
   if (NS_SUCCEEDED(rv)) {
     list->SetInfo(mElement);
-    Swap(val, tmp);
+    std::swap(val, tmp);
   }
   return val;
 }
diff --git a/dom/svg/SVGElement.cpp b/dom/svg/SVGElement.cpp
index 0e9f79a0a1..0a58ca9b38 100644
--- a/dom/svg/SVGElement.cpp
+++ b/dom/svg/SVGElement.cpp
@@ -961,6 +961,7 @@ const Element::MappedAttributeEntry SVGElement::sGraphicsMap[] = {
     {nsGkAtoms::pointer_events},
     {nsGkAtoms::shape_rendering},
     {nsGkAtoms::text_rendering},
+    {nsGkAtoms::transform_origin},
     {nsGkAtoms::visibility},
     {nullptr}};
 
diff --git a/dom/svg/SVGStyleElement.cpp b/dom/svg/SVGStyleElement.cpp
index 01c0c0b0b2..22f1814cad 100644
--- a/dom/svg/SVGStyleElement.cpp
+++ b/dom/svg/SVGStyleElement.cpp
@@ -25,19 +25,18 @@ JSObject* SVGStyleElement::WrapNode(JSContext* aCx,
 
 NS_IMPL_ISUPPORTS_CYCLE_COLLECTION_INHERITED(SVGStyleElement,
                                              SVGStyleElementBase,
-                                             nsIStyleSheetLinkingElement,
                                              nsIMutationObserver)
 
 NS_IMPL_CYCLE_COLLECTION_CLASS(SVGStyleElement)
 
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(SVGStyleElement,
                                                   SVGStyleElementBase)
-  tmp->nsStyleLinkElement::Traverse(cb);
+  tmp->LinkStyle::Traverse(cb);
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
 
 NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(SVGStyleElement,
                                                 SVGStyleElementBase)
-  tmp->nsStyleLinkElement::Unlink();
+  tmp->LinkStyle::Unlink();
 NS_IMPL_CYCLE_COLLECTION_UNLINK_END
 
 //----------------------------------------------------------------------
@@ -170,7 +169,7 @@ void SVGStyleElement::SetTitle(const nsAString& aTitle, ErrorResult& rv) {
 //----------------------------------------------------------------------
 // nsStyleLinkElement methods
 
-Maybe<nsStyleLinkElement::SheetInfo> SVGStyleElement::GetStyleSheetInfo() {
+Maybe<LinkStyle::SheetInfo> SVGStyleElement::GetStyleSheetInfo() {
   if (!IsCSSMimeTypeAttributeForStyleElement(*this)) {
     return Nothing();
   }
diff --git a/dom/svg/SVGStyleElement.h b/dom/svg/SVGStyleElement.h
index 544c7efd16..ef2bae3945 100644
--- a/dom/svg/SVGStyleElement.h
+++ b/dom/svg/SVGStyleElement.h
@@ -6,8 +6,8 @@
 #define mozilla_dom_SVGStyleElement_h
 
 #include "mozilla/Attributes.h"
+#include "mozilla/dom/LinkStyle.h"
 #include "SVGElement.h"
-#include "nsStyleLinkElement.h"
 #include "nsStubMutationObserver.h"
 
 nsresult NS_NewSVGStyleElement(
@@ -19,8 +19,8 @@ namespace dom {
 typedef SVGElement SVGStyleElementBase;
 
 class SVGStyleElement final : public SVGStyleElementBase,
-                              public nsStyleLinkElement,
-                              public nsStubMutationObserver {
+                              public nsStubMutationObserver,
+                              public LinkStyle {
  protected:
   friend nsresult(::NS_NewSVGStyleElement(
       nsIContent** aResult,
@@ -74,7 +74,9 @@ class SVGStyleElement final : public SVGStyleElementBase,
   // completely optimized away.
   inline nsresult Init() { return NS_OK; }
 
-  // nsStyleLinkElement overrides
+  // LinkStyle overrides
+  nsIContent& AsContent() final { return *this; }
+  const LinkStyle* AsLinkStyle() const final { return this; }
   Maybe<SheetInfo> GetStyleSheetInfo() final;
 
   /**
diff --git a/dom/tests/mochitest/ajax/offline/browser_disableAppcache.js b/dom/tests/mochitest/ajax/offline/browser_disableAppcache.js
index 54eb23dcc2..b611431a9d 100644
--- a/dom/tests/mochitest/ajax/offline/browser_disableAppcache.js
+++ b/dom/tests/mochitest/ajax/offline/browser_disableAppcache.js
@@ -2,135 +2,14 @@ const PATH =
   "http://example.com/browser/dom/tests/mochitest/ajax/offline/";
 const URL = PATH + "file_simpleManifest.html";
 const MANIFEST = PATH + "file_simpleManifest.cacheManifest";
-const PREF_INSECURE_APPCACHE = "browser.cache.offline.insecure.enable";
 const PREF_NETWORK_PROXY = "network.proxy.type";
 
-function setSJSState(sjsPath, stateQuery) {
-  let client = new XMLHttpRequest();
-  client.open("GET", sjsPath + "?state=" + stateQuery, false);
-  let appcachechannel = SpecialPowers.wrap(client).channel.QueryInterface(Ci.nsIApplicationCacheChannel);
-
-  return new Promise((resolve, reject) => {
-    client.addEventListener("load", resolve);
-    client.addEventListener("error", reject);
-
-    appcachechannel.chooseApplicationCache = false;
-    appcachechannel.inheritApplicationCache = false;
-    appcachechannel.applicationCache = null;
-
-    client.send();
-  });
-}
-
-add_task(async function() {
-  /* This test loads "evil" content and verified it isn't loaded when appcache is disabled, which emulates loading stale cache from an untrusted network:
-     - Sets frame to load "evil" content
-     - Loads HTML file which also loads and caches content into AppCache
-     - Sets frame to load "good"
-     - Check we still have "evil" content from AppCache
-     - Disables appcache
-     - Check content is "good"
-  */
-  await SpecialPowers.pushPrefEnv({
-    set: [
-      [PREF_INSECURE_APPCACHE, true]
-    ]
-  });
-  await setSJSState(PATH + "file_testFile.sjs", "evil");
-  await BrowserTestUtils.openNewForegroundTab(gBrowser, URL);
-  await ContentTask.spawn(gBrowser.selectedBrowser, null, async () => {
-    let windowPromise = new Promise((resolve, reject) => {
-      function init() {
-        if (content.document.readyState == "complete") {
-          const frame = content.document.getElementById("childframe");
-          const state = frame.contentDocument.getElementById("state");
-          is(state.textContent, "evil", "Loaded evil content");
-          resolve();
-        }
-      }
-      content.document.onreadystatechange = init;
-      init();
-    });
-    let appcachePromise = new Promise((resolve, reject) => {
-      function appcacheInit() {
-        if (content.applicationCache.status === content.applicationCache.IDLE) {
-          ok(true, "Application cache loaded");
-          resolve();
-        } else {
-          info("State was: " + content.applicationCache.status);
-        }
-      }
-      content.applicationCache.oncached = appcacheInit;
-      content.applicationCache.onnoupdate = appcacheInit;
-      content.applicationCache.onerror = () => {
-        ok(false, "Application cache failed");
-        reject();
-      };
-      appcacheInit();
-    });
-    await Promise.all([windowPromise, appcachePromise]);
-  });
-  gBrowser.removeCurrentTab();
-
-  // Turn network and proxy off so we can check the content loads still
-  await setSJSState(PATH + "file_testFile.sjs", "good");
-  Services.cache2.clear();
-
-  // Check we still have the "evil" content despite the state change
-  await BrowserTestUtils.openNewForegroundTab(gBrowser, URL);
-  await ContentTask.spawn(gBrowser.selectedBrowser, null, async () => {
-    const frame = content.document.getElementById("childframe");
-    const state = frame.contentDocument.getElementById("state");
-    is(state.textContent, "evil", "Loaded evil content from cache");
-  });
-  gBrowser.removeCurrentTab();
-
-
-  await SpecialPowers.pushPrefEnv({
-    set: [
-      [PREF_INSECURE_APPCACHE, false]
-    ]
-  });
-  await BrowserTestUtils.openNewForegroundTab(gBrowser, URL);
-
-  // Check that the "good" content is back now appcache is disabled
-  await ContentTask.spawn(gBrowser.selectedBrowser, [URL], async (URL) => {
-    const frame = content.document.getElementById("childframe");
-    const state = frame.contentDocument.getElementById("state");
-    is(state.textContent, "good", "Loaded good content");
-    // Eval is needed to execure in child context.
-    content.window.eval("OfflineTest.clear()");
-  });
-
-  gBrowser.removeCurrentTab();
-  await setSJSState(PATH + "file_testFile.sjs", "");
-  await SpecialPowers.popPrefEnv();
-});
-
 add_task(async function test_pref_removes_api() {
-  await SpecialPowers.pushPrefEnv({
-    set: [
-      [PREF_INSECURE_APPCACHE, true]
-    ]
-  });
   await BrowserTestUtils.openNewForegroundTab(gBrowser, URL);
   await ContentTask.spawn(gBrowser.selectedBrowser, null, async () => {
     // Have to use in page checking as IsSecureContextOrObjectIsFromSecureContext is true for spawn()
-    is(content.document.getElementById("hasAppcache").textContent, "yes", "Appcache is enabled");
-    is(content.document.getElementById("hasOfflineResourceList").textContent, "yes", "OfflineResourceList is enabled");
-  });
-  gBrowser.removeCurrentTab();
-
-  await SpecialPowers.pushPrefEnv({
-    set: [
-      [PREF_INSECURE_APPCACHE, false]
-    ]
-  });
-  await BrowserTestUtils.openNewForegroundTab(gBrowser, URL);
-  await ContentTask.spawn(gBrowser.selectedBrowser, [URL], async (URL) => {
     is(content.document.getElementById("hasAppcache").textContent, "no", "Appcache is disabled");
     is(content.document.getElementById("hasOfflineResourceList").textContent, "no", "OfflineResourceList is disabled");
-    content.window.eval("OfflineTest.clear()");
   });
   gBrowser.removeCurrentTab();
 });
diff --git a/dom/webbrowserpersist/nsWebBrowserPersist.cpp b/dom/webbrowserpersist/nsWebBrowserPersist.cpp
index 9399cca42b..ca259d2239 100644
--- a/dom/webbrowserpersist/nsWebBrowserPersist.cpp
+++ b/dom/webbrowserpersist/nsWebBrowserPersist.cpp
@@ -973,7 +973,6 @@ nsWebBrowserPersist::OnDataAvailable(nsIRequest* request,
 //*****************************************************************************
 
 NS_IMETHODIMP nsWebBrowserPersist::OnProgress(nsIRequest* request,
-                                              nsISupports* ctxt,
                                               int64_t aProgress,
                                               int64_t aProgressMax) {
   if (!mProgressListener) {
@@ -1010,14 +1009,14 @@ NS_IMETHODIMP nsWebBrowserPersist::OnProgress(nsIRequest* request,
   // If our progress listener implements nsIProgressEventSink,
   // forward the notification
   if (mEventSink) {
-    mEventSink->OnProgress(request, ctxt, aProgress, aProgressMax);
+    mEventSink->OnProgress(request, aProgress, aProgressMax);
   }
 
   return NS_OK;
 }
 
 NS_IMETHODIMP nsWebBrowserPersist::OnStatus(nsIRequest* request,
-                                            nsISupports* ctxt, nsresult status,
+                                            nsresult status,
                                             const char16_t* statusArg) {
   if (mProgressListener) {
     // We need to filter out non-error error codes.
@@ -1048,7 +1047,7 @@ NS_IMETHODIMP nsWebBrowserPersist::OnStatus(nsIRequest* request,
   // If our progress listener implements nsIProgressEventSink,
   // forward the notification
   if (mEventSink) {
-    mEventSink->OnStatus(request, ctxt, status, statusArg);
+    mEventSink->OnStatus(request, status, statusArg);
   }
 
   return NS_OK;
diff --git a/dom/webidl/CustomElementRegistry.webidl b/dom/webidl/CustomElementRegistry.webidl
index 34242570b8..194510e609 100644
--- a/dom/webidl/CustomElementRegistry.webidl
+++ b/dom/webidl/CustomElementRegistry.webidl
@@ -12,7 +12,7 @@ interface CustomElementRegistry {
   void setElementCreationCallback(DOMString name, CustomElementCreationCallback callback);
   any get(DOMString name);
   [Throws]
-  Promise<void> whenDefined(DOMString name);
+  Promise<CustomElementConstructor> whenDefined(DOMString name);
   [CEReactions] void upgrade(Node root);
 };
 
diff --git a/dom/webidl/ElementInternals.webidl b/dom/webidl/ElementInternals.webidl
index 2d432796d5..dfeaa097f6 100644
--- a/dom/webidl/ElementInternals.webidl
+++ b/dom/webidl/ElementInternals.webidl
@@ -6,6 +6,7 @@
  * https://html.spec.whatwg.org/#elementinternals
  */
 
-[Pref="dom.webcomponents.elementInternals.enabled", Exposed=Window]
+[Pref="dom.webcomponents.formAssociatedCustomElement.enabled", Exposed=Window]
 interface ElementInternals {
 };
+
diff --git a/dom/webidl/HTMLElement.webidl b/dom/webidl/HTMLElement.webidl
index 63be4802db..76c5eebceb 100644
--- a/dom/webidl/HTMLElement.webidl
+++ b/dom/webidl/HTMLElement.webidl
@@ -63,7 +63,7 @@ interface HTMLElement : Element {
   //readonly attribute boolean? commandChecked;
 
   // https://html.spec.whatwg.org/multipage/custom-elements.html#dom-attachinternals
-  [Pref="dom.webcomponents.elementInternals.enabled", Throws]
+  [Pref="dom.webcomponents.formAssociatedCustomElement.enabled", Throws]
   ElementInternals attachInternals();
 };
 
diff --git a/dom/webidl/HTMLImageElement.webidl b/dom/webidl/HTMLImageElement.webidl
index f96c7ff6e0..9f5b8345ad 100644
--- a/dom/webidl/HTMLImageElement.webidl
+++ b/dom/webidl/HTMLImageElement.webidl
@@ -40,6 +40,8 @@ interface HTMLImageElement : HTMLElement {
            attribute unsigned long height;
            [CEReactions, SetterThrows]
            attribute DOMString decoding;
+           [CEReactions, SetterThrows, Pref="dom.image-lazy-loading.enabled"]
+           attribute DOMString loading;
   readonly attribute unsigned long naturalWidth;
   readonly attribute unsigned long naturalHeight;
   readonly attribute boolean complete;
diff --git a/dom/webidl/HTMLLinkElement.webidl b/dom/webidl/HTMLLinkElement.webidl
index d2fd78e102..756ce0b100 100644
--- a/dom/webidl/HTMLLinkElement.webidl
+++ b/dom/webidl/HTMLLinkElement.webidl
@@ -34,6 +34,10 @@ interface HTMLLinkElement : HTMLElement {
   [CEReactions, SetterThrows, Pure]
            attribute DOMString referrerPolicy;
   [PutForwards=value] readonly attribute DOMTokenList sizes;
+  [CEReactions, SetterThrows, Pure]
+           attribute USVString imageSrcset;
+  [CEReactions, SetterThrows, Pure]
+           attribute USVString imageSizes;
 };
 HTMLLinkElement includes LinkStyle;
 
diff --git a/dom/webidl/OfflineResourceList.webidl b/dom/webidl/OfflineResourceList.webidl
index 7fb2ce8e01..ac26a6fac3 100644
--- a/dom/webidl/OfflineResourceList.webidl
+++ b/dom/webidl/OfflineResourceList.webidl
@@ -2,7 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-[Pref="browser.cache.offline.enable", Func="nsGlobalWindowInner::OfflineCacheAllowedForContext",
+[SecureContext, Pref="browser.cache.offline.enable",
 Exposed=Window]
 interface OfflineResourceList : EventTarget {
   /**
diff --git a/dom/webidl/ResizeObserver.webidl b/dom/webidl/ResizeObserver.webidl
index ba2acce71f..f78c66fc1d 100644
--- a/dom/webidl/ResizeObserver.webidl
+++ b/dom/webidl/ResizeObserver.webidl
@@ -35,8 +35,12 @@ callback ResizeObserverCallback = void (sequence<ResizeObserverEntry> entries, R
 interface ResizeObserverEntry {
     readonly attribute Element target;
     readonly attribute DOMRectReadOnly contentRect;
-    readonly attribute ResizeObserverSize borderBoxSize;
-    readonly attribute ResizeObserverSize contentBoxSize;
+    // We are using [Pure, Cached, Frozen] sequence until `FrozenArray` is implemented.
+    // See https://bugzilla.mozilla.org/show_bug.cgi?id=1236777 for more details.
+    [Frozen, Cached, Pure]
+    readonly attribute sequence<ResizeObserverSize> borderBoxSize;
+    [Frozen, Cached, Pure]
+    readonly attribute sequence<ResizeObserverSize> contentBoxSize;
 };
 
 [Pref="layout.css.resizeobserver.enabled",
diff --git a/dom/webidl/Window.webidl b/dom/webidl/Window.webidl
index 65819006c1..c2bc1a7c45 100644
--- a/dom/webidl/Window.webidl
+++ b/dom/webidl/Window.webidl
@@ -71,7 +71,7 @@ typedef OfflineResourceList ApplicationCache;
 #ifdef HAVE_SIDEBAR
   [Replaceable, Throws] readonly attribute External external;
 #endif
-  [Throws, Pref="browser.cache.offline.enable", Func="nsGlobalWindowInner::OfflineCacheAllowedForContext"] readonly attribute ApplicationCache applicationCache;
+  [Throws, SecureContext, Pref="browser.cache.offline.enable"] readonly attribute ApplicationCache applicationCache;
 
   // user prompts
   [Throws, NeedsSubjectPrincipal] void alert();
diff --git a/dom/websocket/WebSocket.cpp b/dom/websocket/WebSocket.cpp
index 377f958d7c..1d9df9a1fd 100644
--- a/dom/websocket/WebSocket.cpp
+++ b/dom/websocket/WebSocket.cpp
@@ -1683,8 +1683,10 @@ nsresult WebSocketImpl::AsyncOpen(
   MOZ_ASSERT_IF(!aTransportProvider, aNegotiatedExtensions.IsEmpty());
 
   nsCString asciiOrigin;
-  nsresult rv = nsContentUtils::GetASCIIOrigin(aPrincipal, asciiOrigin);
-  NS_ENSURE_SUCCESS(rv, rv);
+  nsresult rv = aPrincipal->GetAsciiOrigin(asciiOrigin);
+  if (NS_FAILED(rv)) {
+    asciiOrigin.AssignLiteral("null");
+  }
 
   if (aTransportProvider) {
     rv = mChannel->SetServerParameters(aTransportProvider,
diff --git a/dom/workers/RuntimeService.cpp b/dom/workers/RuntimeService.cpp
index c1878d128c..b6cc2c121f 100644
--- a/dom/workers/RuntimeService.cpp
+++ b/dom/workers/RuntimeService.cpp
@@ -1180,13 +1180,19 @@ bool RuntimeService::RegisterWorker(WorkerPrivate& aWorkerPrivate) {
   {
     MutexAutoLock lock(mMutex);
 
-    const auto& domainInfo = mDomainMap.LookupForAdd(domain).OrInsert([&domain, parent]() {
-      NS_ASSERTION(!parent, "Shouldn't have a parent here!");
-      Unused << parent;  // silence clang -Wunused-lambda-capture in opt builds
-      WorkerDomainInfo* wdi = new WorkerDomainInfo();
-      wdi->mDomain = domain;
-      return wdi;
-    });
+    auto* const domainInfo =
+        mDomainMap.WithEntryHandle(domain, [&](auto&& entry) {
+          return entry
+              .OrInsertWith([&domain, parent] {
+                NS_ASSERTION(!parent, "Shouldn't have a parent here!");
+                Unused << parent;  // silence clang -Wunused-lambda-capture in
+                                   // opt builds
+                WorkerDomainInfo* wdi = new WorkerDomainInfo();
+                wdi->mDomain = domain;
+                return wdi;
+              })
+              .get();
+        });
 
     queued = gMaxWorkersPerDomain &&
              domainInfo->ActiveWorkerCount() >= gMaxWorkersPerDomain &&
@@ -1247,10 +1253,15 @@ bool RuntimeService::RegisterWorker(WorkerPrivate& aWorkerPrivate) {
     if (!isServiceWorker) {
       // Service workers are excluded since their lifetime is separate from
       // that of dom windows.
-      const auto& windowArray =
-          mWindowMap.LookupForAdd(window).OrInsert(
-              []() { return new nsTArray<WorkerPrivate*>(1); });
-      if (!windowArray->Contains(&aWorkerPrivate)) {
+      if (auto* const windowArray = mWindowMap.WithEntryHandle(
+              window,
+              [](auto&& entry) {
+                return entry
+                    .OrInsertWith(
+                        [] { return new nsTArray<WorkerPrivate*>(1); })
+                    .get();
+              });
+          !windowArray->Contains(&aWorkerPrivate)) {
         windowArray->AppendElement(&aWorkerPrivate);
       } else {
         MOZ_ASSERT(aWorkerPrivate.IsSharedWorker());
diff --git a/dom/workers/ScriptLoader.cpp b/dom/workers/ScriptLoader.cpp
index 7cddd36824..9d7f30fba5 100644
--- a/dom/workers/ScriptLoader.cpp
+++ b/dom/workers/ScriptLoader.cpp
@@ -30,6 +30,7 @@
 #include "js/Exception.h"
 #include "js/SourceText.h"
 #include "nsError.h"
+#include "nsComponentManagerUtils.h"
 #include "nsContentPolicyUtils.h"
 #include "nsContentUtils.h"
 #include "nsDocShellCID.h"
diff --git a/dom/workers/WorkerLoadInfo.cpp b/dom/workers/WorkerLoadInfo.cpp
index f207f28207..daf4996372 100644
--- a/dom/workers/WorkerLoadInfo.cpp
+++ b/dom/workers/WorkerLoadInfo.cpp
@@ -109,8 +109,8 @@ nsresult WorkerLoadInfo::SetPrincipalsAndCSPOnMainThread(
 
   if (mCSP) {
     mCSP->GetAllowsEval(&mReportCSPViolations, &mEvalAllowed);
-    mCSPInfo = new CSPInfo();
-    nsresult rv = CSPToCSPInfo(aCsp, mCSPInfo);
+    mCSPInfo = MakeUnique<CSPInfo>();
+    nsresult rv = CSPToCSPInfo(aCsp, mCSPInfo.get());
     if (NS_WARN_IF(NS_FAILED(rv))) {
       return rv;
     }
@@ -121,18 +121,19 @@ nsresult WorkerLoadInfo::SetPrincipalsAndCSPOnMainThread(
 
   mLoadGroup = aLoadGroup;
 
-  mPrincipalInfo = new PrincipalInfo();
-  mStoragePrincipalInfo = new PrincipalInfo();
+  mPrincipalInfo = MakeUnique<PrincipalInfo>();
+  mStoragePrincipalInfo = MakeUnique<PrincipalInfo>();
   mOriginAttributes = nsContentUtils::GetOriginAttributes(aLoadGroup);
 
-  nsresult rv = PrincipalToPrincipalInfo(aPrincipal, mPrincipalInfo);
+  nsresult rv = PrincipalToPrincipalInfo(aPrincipal, mPrincipalInfo.get());
   NS_ENSURE_SUCCESS(rv, rv);
 
   if (aPrincipal->Equals(aStoragePrincipal)) {
     *mStoragePrincipalInfo = *mPrincipalInfo;
   } else {
-    mStoragePrincipalInfo = new PrincipalInfo();
-    rv = PrincipalToPrincipalInfo(aStoragePrincipal, mStoragePrincipalInfo);
+    mStoragePrincipalInfo = MakeUnique<PrincipalInfo>();
+    rv = PrincipalToPrincipalInfo(aStoragePrincipal,
+                                  mStoragePrincipalInfo.get());
     NS_ENSURE_SUCCESS(rv, rv);
   }
 
diff --git a/dom/workers/WorkerLoadInfo.h b/dom/workers/WorkerLoadInfo.h
index 907fb95dcd..44d2c2d39b 100644
--- a/dom/workers/WorkerLoadInfo.h
+++ b/dom/workers/WorkerLoadInfo.h
@@ -6,6 +6,7 @@
 #define mozilla_dom_workers_WorkerLoadInfo_h
 
 #include "mozilla/StorageAccess.h"
+#include "mozilla/UniquePtr.h"
 #include "mozilla/dom/ChannelInfo.h"
 #include "mozilla/dom/ServiceWorkerRegistrationDescriptor.h"
 #include "mozilla/dom/WorkerCommon.h"
@@ -62,7 +63,7 @@ struct WorkerLoadInfoData {
   // needs to happen on the main thread, but storing the CSPInfo needs to happen
   // on the worker thread. We move the CSPInfo into the Client within
   // ScriptLoader::PreRun().
-  nsAutoPtr<mozilla::ipc::CSPInfo> mCSPInfo;
+  UniquePtr<mozilla::ipc::CSPInfo> mCSPInfo;
 
   nsCOMPtr<nsIChannel> mChannel;
   nsCOMPtr<nsILoadGroup> mLoadGroup;
@@ -98,8 +99,8 @@ struct WorkerLoadInfoData {
   // Only set if we have a custom overriden load group
   RefPtr<InterfaceRequestor> mInterfaceRequestor;
 
-  nsAutoPtr<mozilla::ipc::PrincipalInfo> mPrincipalInfo;
-  nsAutoPtr<mozilla::ipc::PrincipalInfo> mStoragePrincipalInfo;
+  UniquePtr<mozilla::ipc::PrincipalInfo> mPrincipalInfo;
+  UniquePtr<mozilla::ipc::PrincipalInfo> mStoragePrincipalInfo;
   nsCString mDomain;
   nsString mOrigin;  // Derived from mPrincipal; can be used on worker thread.
 
diff --git a/dom/workers/WorkerPrivate.cpp b/dom/workers/WorkerPrivate.cpp
index 75d6c66e4b..81883b473f 100644
--- a/dom/workers/WorkerPrivate.cpp
+++ b/dom/workers/WorkerPrivate.cpp
@@ -47,6 +47,7 @@
 #include "nsCycleCollector.h"
 #include "nsGlobalWindowInner.h"
 #include "nsNetUtil.h"
+#include "nsIFile.h"
 #include "nsIMemoryReporter.h"
 #include "nsIPermissionManager.h"
 #include "nsIScriptError.h"
@@ -122,23 +123,23 @@ const nsIID kDEBUGWorkerEventTargetIID = {
 #endif
 
 template <class T>
-class AutoPtrComparator {
-  typedef nsAutoPtr<T> A;
+class UniquePtrComparator {
+  typedef UniquePtr<T> A;
   typedef T* B;
 
  public:
-  bool Equals(const A& a, const B& b) const {
+  bool Equals(const A& a, const A& b) const {
     return a && b ? *a == *b : !a && !b ? true : false;
   }
-  bool LessThan(const A& a, const B& b) const {
+  bool LessThan(const A& a, const A& b) const {
     return a && b ? *a < *b : b ? true : false;
   }
 };
 
 template <class T>
-inline AutoPtrComparator<T> GetAutoPtrComparator(
-    const nsTArray<nsAutoPtr<T>>&) {
-  return AutoPtrComparator<T>();
+inline UniquePtrComparator<T> GetUniquePtrComparator(
+    const nsTArray<UniquePtr<T>>&) {
+  return UniquePtrComparator<T>();
 }
 
 // This class is used to wrap any runnables that the worker receives via the
@@ -1289,8 +1290,8 @@ void WorkerPrivate::SetCSP(nsIContentSecurityPolicy* aCSP) {
   aCSP->EnsureEventTarget(mMainThreadEventTarget);
 
   mLoadInfo.mCSP = aCSP;
-  mLoadInfo.mCSPInfo = new CSPInfo();
-  nsresult rv = CSPToCSPInfo(mLoadInfo.mCSP, mLoadInfo.mCSPInfo);
+  mLoadInfo.mCSPInfo = MakeUnique<CSPInfo>();
+  nsresult rv = CSPToCSPInfo(mLoadInfo.mCSP, mLoadInfo.mCSPInfo.get());
   if (NS_WARN_IF(NS_FAILED(rv))) {
     return;
   }
@@ -1346,8 +1347,8 @@ nsresult WorkerPrivate::SetCSPFromHeaderValues(
   mLoadInfo.mEvalAllowed = evalAllowed;
   mLoadInfo.mReportCSPViolations = reportEvalViolations;
 
-  mLoadInfo.mCSPInfo = new CSPInfo();
-  rv = CSPToCSPInfo(csp, mLoadInfo.mCSPInfo);
+  mLoadInfo.mCSPInfo = MakeUnique<CSPInfo>();
+  rv = CSPToCSPInfo(csp, mLoadInfo.mCSPInfo.get());
   if (NS_WARN_IF(NS_FAILED(rv))) {
     return rv;
   }
@@ -3583,7 +3584,8 @@ void WorkerPrivate::PropagateFirstPartyStorageAccessGrantedInternal() {
 void WorkerPrivate::TraverseTimeouts(nsCycleCollectionTraversalCallback& cb) {
   MOZ_ACCESS_THREAD_BOUND(mWorkerThreadAccessible, data);
   for (uint32_t i = 0; i < data->mTimeouts.Length(); ++i) {
-    TimeoutInfo* tmp = data->mTimeouts[i];
+    // TODO(erahm): No idea what's going on here.
+    TimeoutInfo* tmp = data->mTimeouts[i].get();
     NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mHandler)
   }
 }
@@ -3800,7 +3802,7 @@ bool WorkerPrivate::RunCurrentSyncLoop() {
   // loop.
   uint32_t currentLoopIndex = mSyncLoopStack.Length() - 1;
 
-  SyncLoopInfo* loopInfo = mSyncLoopStack[currentLoopIndex];
+  SyncLoopInfo* loopInfo = mSyncLoopStack[currentLoopIndex].get();
 
   AutoYieldJSThreadExecution yield;
 
@@ -3872,7 +3874,7 @@ bool WorkerPrivate::RunCurrentSyncLoop() {
   }
 
   // Make sure that the stack didn't change underneath us.
-  MOZ_ASSERT(mSyncLoopStack[currentLoopIndex] == loopInfo);
+  MOZ_ASSERT(mSyncLoopStack[currentLoopIndex].get() == loopInfo);
 
   return DestroySyncLoop(currentLoopIndex);
 }
@@ -3884,7 +3886,7 @@ bool WorkerPrivate::DestroySyncLoop(uint32_t aLoopIndex) {
   AutoYieldJSThreadExecution yield;
 
   // We're about to delete the loop, stash its event target and result.
-  SyncLoopInfo* loopInfo = mSyncLoopStack[aLoopIndex];
+  const auto& loopInfo = mSyncLoopStack[aLoopIndex];
   nsIEventTarget* nestedEventTarget =
       loopInfo->mEventTarget->GetWeakNestedEventTarget();
   MOZ_ASSERT(nestedEventTarget);
@@ -3946,7 +3948,7 @@ void WorkerPrivate::StopSyncLoop(nsIEventTarget* aSyncLoopTarget,
   MOZ_ASSERT(!mSyncLoopStack.IsEmpty());
 
   for (uint32_t index = mSyncLoopStack.Length(); index > 0; index--) {
-    nsAutoPtr<SyncLoopInfo>& loopInfo = mSyncLoopStack[index - 1];
+    const auto& loopInfo = mSyncLoopStack[index - 1];
     MOZ_ASSERT(loopInfo);
     MOZ_ASSERT(loopInfo->mEventTarget);
 
@@ -3985,7 +3987,7 @@ void WorkerPrivate::AssertValidSyncLoop(nsIEventTarget* aSyncLoopTarget) {
     AutoLock lock(mMutex);
 
     for (uint32_t index = 0; index < mSyncLoopStack.Length(); index++) {
-      nsAutoPtr<SyncLoopInfo>& loopInfo = mSyncLoopStack[index];
+      const auto& loopInfo = mSyncLoopStack[index];
       MOZ_ASSERT(loopInfo);
       MOZ_ASSERT(loopInfo->mEventTarget);
 
@@ -4371,7 +4373,7 @@ int32_t WorkerPrivate::SetTimeout(JSContext* aCx, TimeoutHandler* aHandler,
     return timerId;
   }
 
-  nsAutoPtr<TimeoutInfo> newInfo(new TimeoutInfo());
+  auto newInfo = MakeUnique<TimeoutInfo>();
   newInfo->mIsInterval = aIsInterval;
   newInfo->mId = timerId;
 
@@ -4388,8 +4390,8 @@ int32_t WorkerPrivate::SetTimeout(JSContext* aCx, TimeoutHandler* aHandler,
 
   newInfo->mTargetTime = TimeStamp::Now() + newInfo->mInterval;
 
-  nsAutoPtr<TimeoutInfo>* insertedInfo = data->mTimeouts.InsertElementSorted(
-      newInfo.forget(), GetAutoPtrComparator(data->mTimeouts));
+  const auto& insertedInfo = data->mTimeouts.InsertElementSorted(
+      std::move(newInfo), GetUniquePtrComparator(data->mTimeouts));
 
   LOG(TimeoutsLog(), ("Worker %p has new timeout: delay=%d interval=%s\n", this,
                       aTimeout, aIsInterval ? "yes" : "no"));
@@ -4432,7 +4434,7 @@ void WorkerPrivate::ClearTimeout(int32_t aId) {
     NS_ASSERTION(data->mTimerRunning, "Huh?!");
 
     for (uint32_t index = 0; index < data->mTimeouts.Length(); index++) {
-      nsAutoPtr<TimeoutInfo>& info = data->mTimeouts[index];
+      const auto& info = data->mTimeouts[index];
       if (info->mId == aId) {
         info->mCanceled = true;
         break;
@@ -4456,8 +4458,7 @@ bool WorkerPrivate::RunExpiredTimeouts(JSContext* aCx) {
 
   bool retval = true;
 
-  AutoPtrComparator<TimeoutInfo> comparator =
-      GetAutoPtrComparator(data->mTimeouts);
+  auto comparator = GetUniquePtrComparator(data->mTimeouts);
   JS::Rooted<JSObject*> global(aCx, JS::CurrentGlobalOrNull(aCx));
 
   // We want to make sure to run *something*, even if the timer fired a little
@@ -4472,7 +4473,7 @@ bool WorkerPrivate::RunExpiredTimeouts(JSContext* aCx) {
 
   AutoTArray<TimeoutInfo*, 10> expiredTimeouts;
   for (uint32_t index = 0; index < data->mTimeouts.Length(); index++) {
-    nsAutoPtr<TimeoutInfo>& info = data->mTimeouts[index];
+    TimeoutInfo* info = data->mTimeouts[index].get();
     if (info->mTargetTime > now) {
       break;
     }
@@ -4531,7 +4532,7 @@ bool WorkerPrivate::RunExpiredTimeouts(JSContext* aCx) {
   for (uint32_t index = 0, expiredTimeoutIndex = 0,
                 expiredTimeoutLength = expiredTimeouts.Length();
        index < data->mTimeouts.Length();) {
-    nsAutoPtr<TimeoutInfo>& info = data->mTimeouts[index];
+    const auto& info = data->mTimeouts[index];
     if ((expiredTimeoutIndex < expiredTimeoutLength &&
          info == expiredTimeouts[expiredTimeoutIndex] &&
          ++expiredTimeoutIndex) ||
diff --git a/dom/workers/WorkerPrivate.h b/dom/workers/WorkerPrivate.h
index cabfab0349..a0ed92c3a7 100644
--- a/dom/workers/WorkerPrivate.h
+++ b/dom/workers/WorkerPrivate.h
@@ -12,6 +12,7 @@
 #include "mozilla/DOMEventTargetHelper.h"
 #include "mozilla/RelativeTimeline.h"
 #include "mozilla/StorageAccess.h"
+#include "mozilla/UniquePtr.h"
 #include "nsContentUtils.h"
 #include "nsIContentSecurityPolicy.h"
 #include "nsIEventTarget.h"
@@ -1059,7 +1060,7 @@ class WorkerPrivate : public RelativeTimeline {
   // This is only modified on the worker thread, but in DEBUG builds
   // AssertValidSyncLoop function iterates it on other threads. Therefore
   // modifications are done with mMutex held *only* in DEBUG builds.
-  nsTArray<nsAutoPtr<SyncLoopInfo>> mSyncLoopStack;
+  nsTArray<UniquePtr<SyncLoopInfo>> mSyncLoopStack;
 
   nsCOMPtr<nsITimer> mCancelingTimer;
 
@@ -1098,7 +1099,7 @@ class WorkerPrivate : public RelativeTimeline {
     RefPtr<WorkerDebuggerGlobalScope> mDebuggerScope;
     nsTArray<WorkerPrivate*> mChildWorkers;
     nsTObserverArray<WorkerRef*> mWorkerRefs;
-    nsTArray<nsAutoPtr<TimeoutInfo>> mTimeouts;
+    nsTArray<UniquePtr<TimeoutInfo>> mTimeouts;
 
     nsCOMPtr<nsITimer> mTimer;
     nsCOMPtr<nsITimerCallback> mTimerRunnable;
diff --git a/dom/workers/remoteworkers/RemoteWorkerChild.cpp b/dom/workers/remoteworkers/RemoteWorkerChild.cpp
index 31e4194c7f..b14be607d8 100644
--- a/dom/workers/remoteworkers/RemoteWorkerChild.cpp
+++ b/dom/workers/remoteworkers/RemoteWorkerChild.cpp
@@ -207,8 +207,9 @@ nsresult RemoteWorkerChild::ExecWorkerOnMainThread(
   info.mBaseURI = DeserializeURI(aData.baseScriptURL());
   info.mResolvedScriptURI = DeserializeURI(aData.resolvedScriptURL());
 
-  info.mPrincipalInfo = new PrincipalInfo(aData.principalInfo());
-  info.mStoragePrincipalInfo = new PrincipalInfo(aData.storagePrincipalInfo());
+  info.mPrincipalInfo = MakeUnique<PrincipalInfo>(aData.principalInfo());
+  info.mStoragePrincipalInfo =
+      MakeUnique<PrincipalInfo>(aData.storagePrincipalInfo());
 
   info.mReferrerInfo = aData.referrerInfo();
   info.mDomain = aData.domain();
@@ -243,8 +244,8 @@ nsresult RemoteWorkerChild::ExecWorkerOnMainThread(
     Maybe<mozilla::ipc::CSPInfo> cspInfo = clientInfo.ref().GetCspInfo();
     if (cspInfo.isSome()) {
       info.mCSP = CSPInfoToCSP(cspInfo.ref(), nullptr);
-      info.mCSPInfo = new CSPInfo();
-      rv = CSPToCSPInfo(info.mCSP, info.mCSPInfo);
+      info.mCSPInfo = MakeUnique<CSPInfo>();
+      rv = CSPToCSPInfo(info.mCSP, info.mCSPInfo.get());
       if (NS_WARN_IF(NS_FAILED(rv))) {
         return rv;
       }
diff --git a/dom/worklet/Worklet.cpp b/dom/worklet/Worklet.cpp
index a0d9a2732e..f936e65de9 100644
--- a/dom/worklet/Worklet.cpp
+++ b/dom/worklet/Worklet.cpp
@@ -10,6 +10,7 @@
 #include "mozilla/dom/BlobBinding.h"
 #include "mozilla/dom/Fetch.h"
 #include "mozilla/dom/PromiseNativeHandler.h"
+#include "mozilla/dom/Request.h"
 #include "mozilla/dom/Response.h"
 #include "mozilla/dom/ScriptSettings.h"
 #include "mozilla/dom/ScriptLoader.h"
@@ -67,10 +68,9 @@ class WorkletFetchHandler final : public PromiseNativeHandler,
  public:
   NS_DECL_THREADSAFE_ISUPPORTS
 
-  static already_AddRefed<Promise> Fetch(Worklet* aWorklet,
+  static already_AddRefed<Promise> Fetch(Worklet* aWorklet, JSContext* aCx,
                                          const nsAString& aModuleURL,
                                          const WorkletOptions& aOptions,
-                                         CallerType aCallerType,
                                          ErrorResult& aRv) {
     MOZ_ASSERT(aWorklet);
     MOZ_ASSERT(NS_IsMainThread());
@@ -118,14 +118,25 @@ class WorkletFetchHandler final : public PromiseNativeHandler,
       }
     }
 
-    RequestOrUSVString request;
-    request.SetAsUSVString().ShareOrDependUpon(aModuleURL);
+    RequestOrUSVString requestInput;
+    requestInput.SetAsUSVString().ShareOrDependUpon(aModuleURL);
 
-    RequestInit init;
-    init.mCredentials.Construct(aOptions.mCredentials);
+    RequestInit requestInit;
+    requestInit.mCredentials.Construct(aOptions.mCredentials);
 
-    RefPtr<Promise> fetchPromise =
-        FetchRequest(global, request, init, aCallerType, aRv);
+    RefPtr<Request> request =
+        Request::Constructor(global, aCx, requestInput, requestInit, aRv);
+    if (aRv.Failed()) {
+      return nullptr;
+    }
+
+    request->OverrideContentPolicyType(aWorklet->Impl()->ContentPolicyType());
+
+    RequestOrUSVString finalRequestInput;
+    finalRequestInput.SetAsRequest() = request;
+
+    RefPtr<Promise> fetchPromise = FetchRequest(
+        global, finalRequestInput, requestInit, CallerType::System, aRv);
     if (NS_WARN_IF(aRv.Failed())) {
       // OK to just return null, since caller will ignore return value
       // anyway if aRv is a failure.
@@ -445,13 +456,13 @@ JSObject* Worklet::WrapObject(JSContext* aCx,
   return mImpl->WrapWorklet(aCx, this, aGivenProto);
 }
 
-already_AddRefed<Promise> Worklet::AddModule(const nsAString& aModuleURL,
+already_AddRefed<Promise> Worklet::AddModule(JSContext* aCx,
+                                             const nsAString& aModuleURL,
                                              const WorkletOptions& aOptions,
                                              CallerType aCallerType,
                                              ErrorResult& aRv) {
   MOZ_ASSERT(NS_IsMainThread());
-  return WorkletFetchHandler::Fetch(this, aModuleURL, aOptions, aCallerType,
-                                    aRv);
+  return WorkletFetchHandler::Fetch(this, aCx, aModuleURL, aOptions, aRv);
 }
 
 WorkletFetchHandler* Worklet::GetImportFetchHandler(const nsACString& aURI) {
diff --git a/dom/worklet/Worklet.h b/dom/worklet/Worklet.h
index 83f63cc212..98a1d69d9c 100644
--- a/dom/worklet/Worklet.h
+++ b/dom/worklet/Worklet.h
@@ -40,7 +40,8 @@ class Worklet final : public nsISupports, public nsWrapperCache {
   virtual JSObject* WrapObject(JSContext* aCx,
                                JS::Handle<JSObject*> aGivenProto) override;
 
-  already_AddRefed<Promise> AddModule(const nsAString& aModuleURL,
+  already_AddRefed<Promise> AddModule(JSContext* aCx,
+                                      const nsAString& aModuleURL,
                                       const WorkletOptions& aOptions,
                                       CallerType aCallerType, ErrorResult& aRv);
 
diff --git a/dom/worklet/WorkletImpl.h b/dom/worklet/WorkletImpl.h
index cc723b83f0..9424c02682 100644
--- a/dom/worklet/WorkletImpl.h
+++ b/dom/worklet/WorkletImpl.h
@@ -61,6 +61,8 @@ class WorkletImpl {
 
   void NotifyWorkletFinished();
 
+  virtual nsContentPolicyType ContentPolicyType() const = 0;
+
   // Execution thread only.
   dom::WorkletGlobalScope* GetGlobalScope();
 
diff --git a/dom/xhr/XMLHttpRequestMainThread.cpp b/dom/xhr/XMLHttpRequestMainThread.cpp
index 1258308e79..5e9ca691b5 100644
--- a/dom/xhr/XMLHttpRequestMainThread.cpp
+++ b/dom/xhr/XMLHttpRequestMainThread.cpp
@@ -2495,6 +2495,31 @@ nsresult XMLHttpRequestMainThread::InitiateFetch(
   nsresult rv;
   nsCOMPtr<nsIInputStream> uploadStream = std::move(aUploadStream);
 
+  if (!uploadStream) {
+    RefPtr<PreloaderBase> preload = FindPreload();
+    if (preload) {
+      // Because of bug 682305, we can't let listener be the XHR object itself
+      // because JS wouldn't be able to use it. So create a listener around
+      // 'this'. Make sure to hold a strong reference so that we don't leak the
+      // wrapper.
+      nsCOMPtr<nsIStreamListener> listener =
+          new net::nsStreamListenerWrapper(this);
+      rv = preload->AsyncConsume(listener);
+      if (NS_SUCCEEDED(rv)) {
+        mFromPreload = true;
+
+        // May be null when the preload has already finished, but the XHR code
+        // is safe to live with it.
+        mChannel = preload->Channel();
+        MOZ_ASSERT(mChannel);
+        EnsureChannelContentType();
+        return NS_OK;
+      }
+
+      preload = nullptr;
+    }
+  }
+
   // nsIRequest::LOAD_BACKGROUND prevents throbber from becoming active, which
   // in turn keeps STOP button from becoming active.  If the consumer passed in
   // a progress event handler we must load with nsIRequest::LOAD_NORMAL or
@@ -2515,7 +2540,7 @@ nsresult XMLHttpRequestMainThread::InitiateFetch(
       mAuthorRequestHeaders.Set("accept", NS_LITERAL_CSTRING("*/*"));
     }
 
-    mAuthorRequestHeaders.ApplyToChannel(httpChannel);
+    mAuthorRequestHeaders.ApplyToChannel(httpChannel, false);
 
     if (!IsSystemXHR()) {
       nsCOMPtr<nsPIDOMWindowInner> owner = GetOwner();
@@ -2634,17 +2659,7 @@ nsresult XMLHttpRequestMainThread::InitiateFetch(
     AddLoadFlags(mChannel, nsICachingChannel::LOAD_BYPASS_LOCAL_CACHE_IF_BUSY);
   }
 
-  // Since we expect XML data, set the type hint accordingly
-  // if the channel doesn't know any content type.
-  // This means that we always try to parse local files as XML
-  // ignoring return value, as this is not critical. Use text/xml as fallback
-  // MIME type.
-  nsAutoCString contentType;
-  if (NS_FAILED(mChannel->GetContentType(contentType)) ||
-      contentType.IsEmpty() ||
-      contentType.EqualsLiteral(UNKNOWN_CONTENT_TYPE)) {
-    mChannel->SetContentType(NS_LITERAL_CSTRING("text/xml"));
-  }
+  EnsureChannelContentType();
 
   // Set up the preflight if needed
   if (!IsSystemXHR()) {
@@ -2700,6 +2715,58 @@ nsresult XMLHttpRequestMainThread::InitiateFetch(
   return NS_OK;
 }
 
+already_AddRefed<PreloaderBase> XMLHttpRequestMainThread::FindPreload() {
+  Document* doc = GetDocumentIfCurrent();
+  if (!doc) {
+    return nullptr;
+  }
+  if (mPrincipal->IsSystemPrincipal() || IsSystemXHR()) {
+    return nullptr;
+  }
+  if (!mRequestMethod.EqualsLiteral("GET")) {
+    // Preload can only do GET.
+    return nullptr;
+  }
+  if (!mAuthorRequestHeaders.IsEmpty()) {
+    // Preload can't set headers.
+    return nullptr;
+  }
+
+  // mIsAnon overrules mFlagACwithCredentials.
+  CORSMode cors = (mIsAnon || !mFlagACwithCredentials)
+                      ? CORSMode::CORS_ANONYMOUS
+                      : CORSMode::CORS_USE_CREDENTIALS;
+  nsCOMPtr<nsIReferrerInfo> referrerInfo =
+      ReferrerInfo::CreateForFetch(mPrincipal, doc);
+  auto key = PreloadHashKey::CreateAsFetch(mRequestURL, cors,
+                                           referrerInfo->ReferrerPolicy());
+  RefPtr<PreloaderBase> preload = doc->Preloads().LookupPreload(&key);
+  if (!preload) {
+    return nullptr;
+  }
+
+  preload->RemoveSelf(doc);
+  preload->NotifyUsage(PreloaderBase::LoadBackground::Keep);
+
+  return preload.forget();
+}
+
+void XMLHttpRequestMainThread::EnsureChannelContentType() {
+  MOZ_ASSERT(mChannel);
+
+  // Since we expect XML data, set the type hint accordingly
+  // if the channel doesn't know any content type.
+  // This means that we always try to parse local files as XML
+  // ignoring return value, as this is not critical. Use text/xml as fallback
+  // MIME type.
+  nsAutoCString contentType;
+  if (NS_FAILED(mChannel->GetContentType(contentType)) ||
+      contentType.IsEmpty() ||
+      contentType.EqualsLiteral(UNKNOWN_CONTENT_TYPE)) {
+    mChannel->SetContentType(NS_LITERAL_CSTRING("text/xml"));
+  }
+}
+
 void XMLHttpRequestMainThread::UnsuppressEventHandlingAndResume() {
   MOZ_ASSERT(NS_IsMainThread());
   MOZ_ASSERT(mFlagSynchronous);
@@ -3235,13 +3302,19 @@ nsresult XMLHttpRequestMainThread::OnRedirectVerifyCallback(nsresult result) {
   NS_ASSERTION(mNewRedirectChannel, "mNewRedirectChannel not set in callback");
 
   if (NS_SUCCEEDED(result)) {
+    bool rewriteToGET = false;
+    nsCOMPtr<nsIHttpChannel> oldHttpChannel = GetCurrentHttpChannel();
+    // Fetch 4.4.11
+    Unused << oldHttpChannel->ShouldStripRequestBodyHeader(mRequestMethod,
+                                                           &rewriteToGET);
+
     mChannel = mNewRedirectChannel;
 
-    nsCOMPtr<nsIHttpChannel> httpChannel(do_QueryInterface(mChannel));
-    if (httpChannel) {
+    nsCOMPtr<nsIHttpChannel> newHttpChannel(do_QueryInterface(mChannel));
+    if (newHttpChannel) {
       // Ensure all original headers are duplicated for the new channel (bug
       // #553888)
-      mAuthorRequestHeaders.ApplyToChannel(httpChannel);
+      mAuthorRequestHeaders.ApplyToChannel(newHttpChannel, rewriteToGET);
     }
   } else {
     mErrorLoad = ErrorType::eRedirect;
@@ -3263,8 +3336,7 @@ nsresult XMLHttpRequestMainThread::OnRedirectVerifyCallback(nsresult result) {
 //
 
 NS_IMETHODIMP
-XMLHttpRequestMainThread::OnProgress(nsIRequest* aRequest,
-                                     nsISupports* aContext, int64_t aProgress,
+XMLHttpRequestMainThread::OnProgress(nsIRequest* aRequest, int64_t aProgress,
                                      int64_t aProgressMax) {
   // When uploading, OnProgress reports also headers in aProgress and
   // aProgressMax. So, try to remove the headers, if possible.
@@ -3289,18 +3361,17 @@ XMLHttpRequestMainThread::OnProgress(nsIRequest* aRequest,
   }
 
   if (mProgressEventSink) {
-    mProgressEventSink->OnProgress(aRequest, aContext, aProgress, aProgressMax);
+    mProgressEventSink->OnProgress(aRequest, aProgress, aProgressMax);
   }
 
   return NS_OK;
 }
 
 NS_IMETHODIMP
-XMLHttpRequestMainThread::OnStatus(nsIRequest* aRequest, nsISupports* aContext,
-                                   nsresult aStatus,
+XMLHttpRequestMainThread::OnStatus(nsIRequest* aRequest, nsresult aStatus,
                                    const char16_t* aStatusArg) {
   if (mProgressEventSink) {
-    mProgressEventSink->OnStatus(aRequest, aContext, aStatus, aStatusArg);
+    mProgressEventSink->OnStatus(aRequest, aStatus, aStatusArg);
   }
 
   return NS_OK;
@@ -3886,6 +3957,8 @@ RequestHeaders::RequestHeader* RequestHeaders::Find(const nsACString& aName) {
   return nullptr;
 }
 
+bool RequestHeaders::IsEmpty() const { return mHeaders.IsEmpty(); }
+
 bool RequestHeaders::Has(const char* aName) {
   return Has(nsDependentCString(aName));
 }
@@ -3937,15 +4010,22 @@ void RequestHeaders::MergeOrSet(const nsACString& aName,
 
 void RequestHeaders::Clear() { mHeaders.Clear(); }
 
-void RequestHeaders::ApplyToChannel(nsIHttpChannel* aHttpChannel) const {
+void RequestHeaders::ApplyToChannel(nsIHttpChannel* aChannel,
+                                    bool aStripRequestBodyHeader) const {
   for (const RequestHeader& header : mHeaders) {
+    if (aStripRequestBodyHeader &&
+        (header.mName.LowerCaseEqualsASCII("content-type") ||
+         header.mName.LowerCaseEqualsASCII("content-encoding") ||
+         header.mName.LowerCaseEqualsASCII("content-language") ||
+         header.mName.LowerCaseEqualsASCII("content-location"))) {
+      continue;
+    }
     if (header.mValue.IsEmpty()) {
-      DebugOnly<nsresult> rv =
-          aHttpChannel->SetEmptyRequestHeader(header.mName);
+      DebugOnly<nsresult> rv = aChannel->SetEmptyRequestHeader(header.mName);
       MOZ_ASSERT(NS_SUCCEEDED(rv));
     } else {
       DebugOnly<nsresult> rv =
-          aHttpChannel->SetRequestHeader(header.mName, header.mValue, false);
+          aChannel->SetRequestHeader(header.mName, header.mValue, false);
       MOZ_ASSERT(NS_SUCCEEDED(rv));
     }
   }
diff --git a/dom/xhr/XMLHttpRequestMainThread.h b/dom/xhr/XMLHttpRequestMainThread.h
index 6afe0ffa3d..0ed966f87b 100644
--- a/dom/xhr/XMLHttpRequestMainThread.h
+++ b/dom/xhr/XMLHttpRequestMainThread.h
@@ -153,6 +153,7 @@ class RequestHeaders {
     bool Next();
   };
 
+  bool IsEmpty() const;
   bool Has(const char* aName);
   bool Has(const nsACString& aName);
   void Get(const char* aName, nsACString& aValue);
@@ -162,7 +163,8 @@ class RequestHeaders {
   void MergeOrSet(const char* aName, const nsACString& aValue);
   void MergeOrSet(const nsACString& aName, const nsACString& aValue);
   void Clear();
-  void ApplyToChannel(nsIHttpChannel* aChannel) const;
+  void ApplyToChannel(nsIHttpChannel* aChannel,
+                      bool aStripRequestBodyHeader) const;
   void GetCORSUnsafeHeaders(nsTArray<nsCString>& aArray) const;
 };
 
@@ -462,7 +464,14 @@ class XMLHttpRequestMainThread final : public XMLHttpRequest,
   // determines if the onreadystatechange listener should be called.
   nsresult ChangeState(uint16_t aState, bool aBroadcast = true);
   already_AddRefed<nsILoadGroup> GetLoadGroup() const;
-  nsIURI* GetBaseURI();
+
+  // Finds a preload for this XHR.  If it is found it's removed from the preload
+  // table of the document and marked as used.  The called doesn't need to do
+  // any more comparative checks.
+  already_AddRefed<PreloaderBase> FindPreload();
+  // If no or unknown mime type is set on the channel this method ensures it's
+  // set to "text/xml".
+  void EnsureChannelContentType();
 
   already_AddRefed<nsIHttpChannel> GetCurrentHttpChannel();
   already_AddRefed<nsIJARChannel> GetCurrentJARChannel();
@@ -752,6 +761,10 @@ class XMLHttpRequestMainThread final : public XMLHttpRequest,
   // processed all the bytes and the EOF.
   bool mEofDecoded;
 
+  // This flag will be set in `Send()` when we successfully reuse a "fetch"
+  // preload to satisfy this XHR.
+  bool mFromPreload = false;
+
   // Our parse-end listener, if we are parsing.
   RefPtr<nsXHRParseEndListener> mParseEndListener;
 
diff --git a/dom/xml/CDATASection.cpp b/dom/xml/CDATASection.cpp
index 149d51644e..19f5874a1e 100644
--- a/dom/xml/CDATASection.cpp
+++ b/dom/xml/CDATASection.cpp
@@ -9,7 +9,7 @@
 namespace mozilla {
 namespace dom {
 
-CDATASection::~CDATASection() {}
+CDATASection::~CDATASection() = default;
 
 JSObject* CDATASection::WrapNode(JSContext* aCx,
                                  JS::Handle<JSObject*> aGivenProto) {
diff --git a/dom/xml/ProcessingInstruction.cpp b/dom/xml/ProcessingInstruction.cpp
index fb7a6ba235..ce59f94aeb 100644
--- a/dom/xml/ProcessingInstruction.cpp
+++ b/dom/xml/ProcessingInstruction.cpp
@@ -4,6 +4,7 @@
 
 #include "nsGkAtoms.h"
 #include "nsUnicharUtils.h"
+#include "mozilla/dom/LinkStyle.h"
 #include "mozilla/dom/ProcessingInstruction.h"
 #include "mozilla/dom/ProcessingInstructionBinding.h"
 #include "mozilla/dom/XMLStylesheetProcessingInstruction.h"
@@ -53,11 +54,14 @@ ProcessingInstruction::ProcessingInstruction(
                   false);  // Don't notify (bug 420429).
 }
 
-ProcessingInstruction::~ProcessingInstruction() {}
+ProcessingInstruction::~ProcessingInstruction() = default;
 
-// If you add nsIStyleSheetLinkingElement here, make sure we actually
-// implement the nsStyleLinkElement methods.
-NS_IMPL_ISUPPORTS_INHERITED0(ProcessingInstruction, CharacterData)
+StyleSheet* ProcessingInstruction::GetSheet() const {
+  if (const auto* linkStyle = LinkStyle::FromNode(*this)) {
+    return linkStyle->GetSheet();
+  }
+  return nullptr;
+}
 
 JSObject* ProcessingInstruction::WrapNode(JSContext* aCx,
                                           JS::Handle<JSObject*> aGivenProto) {
@@ -80,16 +84,6 @@ already_AddRefed<CharacterData> ProcessingInstruction::CloneDataNode(
   return do_AddRef(new (nim) ProcessingInstruction(ni.forget(), data));
 }
 
-Maybe<nsStyleLinkElement::SheetInfo>
-ProcessingInstruction::GetStyleSheetInfo() {
-  MOZ_ASSERT_UNREACHABLE(
-      "XMLStylesheetProcessingInstruction should override "
-      "this and we don't try to do stylesheet stuff.  In "
-      "particular, we do not implement "
-      "nsIStyleSheetLinkingElement");
-  return Nothing();
-}
-
 #ifdef DEBUG
 void ProcessingInstruction::List(FILE* out, int32_t aIndent) const {
   int32_t index;
diff --git a/dom/xml/ProcessingInstruction.h b/dom/xml/ProcessingInstruction.h
index b5583b55bf..dc027410ec 100644
--- a/dom/xml/ProcessingInstruction.h
+++ b/dom/xml/ProcessingInstruction.h
@@ -8,25 +8,23 @@
 #include "mozilla/Attributes.h"
 #include "mozilla/dom/CharacterData.h"
 #include "nsAString.h"
-#include "nsStyleLinkElement.h"
 
 class nsIPrincipal;
 class nsIURI;
 
 namespace mozilla {
+
+class StyleSheet;
+
 namespace dom {
 
-class ProcessingInstruction : public CharacterData, public nsStyleLinkElement {
+class ProcessingInstruction : public CharacterData {
  public:
   ProcessingInstruction(already_AddRefed<mozilla::dom::NodeInfo>&& aNodeInfo,
                         const nsAString& aData);
 
-  // nsISupports.  We need to declare QI, because nsStyleLinkElement
-  // has a pure-virtual QI.
-  NS_DECL_ISUPPORTS_INHERITED
-
   virtual already_AddRefed<CharacterData> CloneDataNode(
-      mozilla::dom::NodeInfo* aNodeInfo, bool aCloneText) const override;
+      dom::NodeInfo* aNodeInfo, bool aCloneText) const override;
 
 #ifdef DEBUG
   virtual void List(FILE* out, int32_t aIndent) const override;
@@ -36,6 +34,9 @@ class ProcessingInstruction : public CharacterData, public nsStyleLinkElement {
 
   // WebIDL API
   void GetTarget(nsAString& aTarget) { aTarget = NodeName(); }
+  // This is the WebIDL API for LinkStyle, even though only
+  // XMLStylesheetProcessingInstruction actually implements LinkStyle.
+  StyleSheet* GetSheet() const;
 
   NS_IMPL_FROMNODE_HELPER(ProcessingInstruction, IsProcessingInstruction())
 
@@ -54,11 +55,7 @@ class ProcessingInstruction : public CharacterData, public nsStyleLinkElement {
    */
   bool GetAttrValue(nsAtom* aName, nsAString& aValue);
 
-  virtual JSObject* WrapNode(JSContext* aCx,
-                             JS::Handle<JSObject*> aGivenProto) override;
-
-  // nsStyleLinkElement overrides, because we can't leave them pure virtual.
-  Maybe<SheetInfo> GetStyleSheetInfo() override;
+  JSObject* WrapNode(JSContext*, JS::Handle<JSObject*> aGivenProto) override;
 };
 
 }  // namespace dom
diff --git a/dom/xml/XMLDocument.cpp b/dom/xml/XMLDocument.cpp
index 73e99689b2..c85fa9044b 100644
--- a/dom/xml/XMLDocument.cpp
+++ b/dom/xml/XMLDocument.cpp
@@ -25,6 +25,7 @@
 #include "nsThreadUtils.h"
 #include "nsJSUtils.h"
 #include "nsCRT.h"
+#include "nsComponentManagerUtils.h"
 #include "nsContentCreatorFunctions.h"
 #include "nsContentPolicyUtils.h"
 #include "nsIConsoleService.h"
diff --git a/dom/xml/XMLStylesheetProcessingInstruction.cpp b/dom/xml/XMLStylesheetProcessingInstruction.cpp
index 44398693f7..2065586344 100644
--- a/dom/xml/XMLStylesheetProcessingInstruction.cpp
+++ b/dom/xml/XMLStylesheetProcessingInstruction.cpp
@@ -11,23 +11,23 @@ namespace dom {
 
 // nsISupports implementation
 
-NS_IMPL_ISUPPORTS_CYCLE_COLLECTION_INHERITED(XMLStylesheetProcessingInstruction,
-                                             ProcessingInstruction,
-                                             nsIStyleSheetLinkingElement)
+NS_IMPL_ISUPPORTS_CYCLE_COLLECTION_INHERITED_0(
+    XMLStylesheetProcessingInstruction, ProcessingInstruction)
 
 NS_IMPL_CYCLE_COLLECTION_CLASS(XMLStylesheetProcessingInstruction)
 
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(
     XMLStylesheetProcessingInstruction, ProcessingInstruction)
-  tmp->nsStyleLinkElement::Traverse(cb);
+  tmp->LinkStyle::Traverse(cb);
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
 
 NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(
     XMLStylesheetProcessingInstruction, ProcessingInstruction)
-  tmp->nsStyleLinkElement::Unlink();
+  tmp->LinkStyle::Unlink();
 NS_IMPL_CYCLE_COLLECTION_UNLINK_END
 
-XMLStylesheetProcessingInstruction::~XMLStylesheetProcessingInstruction() {}
+XMLStylesheetProcessingInstruction::~XMLStylesheetProcessingInstruction() =
+    default;
 
 // nsIContent
 
@@ -61,7 +61,7 @@ void XMLStylesheetProcessingInstruction::SetNodeValueInternal(
   }
 }
 
-// nsStyleLinkElement
+// LinkStyle
 
 void XMLStylesheetProcessingInstruction::GetCharset(nsAString& aCharset) {
   if (!GetAttrValue(nsGkAtoms::charset, aCharset)) {
@@ -69,12 +69,11 @@ void XMLStylesheetProcessingInstruction::GetCharset(nsAString& aCharset) {
   }
 }
 
-/* virtual */
 void XMLStylesheetProcessingInstruction::OverrideBaseURI(nsIURI* aNewBaseURI) {
   mOverriddenBaseURI = aNewBaseURI;
 }
 
-Maybe<nsStyleLinkElement::SheetInfo>
+Maybe<LinkStyle::SheetInfo>
 XMLStylesheetProcessingInstruction::GetStyleSheetInfo() {
   // xml-stylesheet PI is special only in prolog
   if (!nsContentUtils::InProlog(this)) {
diff --git a/dom/xml/XMLStylesheetProcessingInstruction.h b/dom/xml/XMLStylesheetProcessingInstruction.h
index a765d63f6d..472f6fd10f 100644
--- a/dom/xml/XMLStylesheetProcessingInstruction.h
+++ b/dom/xml/XMLStylesheetProcessingInstruction.h
@@ -7,14 +7,15 @@
 
 #include "mozilla/Attributes.h"
 #include "mozilla/Unused.h"
+#include "mozilla/dom/LinkStyle.h"
 #include "mozilla/dom/ProcessingInstruction.h"
 #include "nsIURI.h"
-#include "nsStyleLinkElement.h"
 
 namespace mozilla {
 namespace dom {
 
-class XMLStylesheetProcessingInstruction final : public ProcessingInstruction {
+class XMLStylesheetProcessingInstruction final : public ProcessingInstruction,
+                                                 public LinkStyle {
  public:
   XMLStylesheetProcessingInstruction(
       already_AddRefed<mozilla::dom::NodeInfo>&& aNodeInfo,
@@ -30,10 +31,8 @@ class XMLStylesheetProcessingInstruction final : public ProcessingInstruction {
                 nsGkAtoms::xml_stylesheet),
             aData) {}
 
-  // nsISupports
-  NS_DECL_ISUPPORTS_INHERITED
-
   // CC
+  NS_DECL_ISUPPORTS_INHERITED
   NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(XMLStylesheetProcessingInstruction,
                                            ProcessingInstruction)
 
@@ -45,10 +44,16 @@ class XMLStylesheetProcessingInstruction final : public ProcessingInstruction {
   virtual nsresult BindToTree(BindContext&, nsINode& aParent) override;
   virtual void UnbindFromTree(bool aNullParent = true) override;
 
-  // nsIStyleSheetLinkingElement
-  virtual void OverrideBaseURI(nsIURI* aNewBaseURI) override;
+  /**
+   * Tells this processing instruction to use a different base URI. This is used
+   * for proper loading of xml-stylesheet processing instructions in XUL
+   * overlays and is only currently used by nsXMLStylesheetPI.
+   *
+   * @param aNewBaseURI the new base URI, nullptr to use the default base URI.
+   */
+  void OverrideBaseURI(nsIURI* aNewBaseURI);
 
-  // nsStyleLinkElement
+  // LinkStyle
   void GetCharset(nsAString& aCharset) override;
 
   virtual void SetData(const nsAString& aData,
@@ -65,6 +70,8 @@ class XMLStylesheetProcessingInstruction final : public ProcessingInstruction {
 
   nsCOMPtr<nsIURI> mOverriddenBaseURI;
 
+  nsIContent& AsContent() final { return *this; }
+  const LinkStyle* AsLinkStyle() const final { return this; }
   Maybe<SheetInfo> GetStyleSheetInfo() final;
 
   already_AddRefed<CharacterData> CloneDataNode(
diff --git a/dom/xml/nsXMLContentSink.cpp b/dom/xml/nsXMLContentSink.cpp
index 38143da061..5744f34d25 100644
--- a/dom/xml/nsXMLContentSink.cpp
+++ b/dom/xml/nsXMLContentSink.cpp
@@ -9,7 +9,6 @@
 #include "nsIContent.h"
 #include "nsIURI.h"
 #include "nsNetUtil.h"
-#include "nsIStyleSheetLinkingElement.h"
 #include "nsHTMLParts.h"
 #include "nsCRT.h"
 #include "mozilla/StyleSheetInlines.h"
@@ -25,7 +24,6 @@
 #include "mozilla/Logging.h"
 #include "nsRect.h"
 #include "nsIScriptElement.h"
-#include "nsStyleLinkElement.h"
 #include "nsReadableUtils.h"
 #include "nsUnicharUtils.h"
 #include "nsIChannel.h"
@@ -91,7 +89,7 @@ nsXMLContentSink::nsXMLContentSink()
   PodArrayZero(mText);
 }
 
-nsXMLContentSink::~nsXMLContentSink() {}
+nsXMLContentSink::~nsXMLContentSink() = default;
 
 nsresult nsXMLContentSink::Init(Document* aDoc, nsIURI* aURI,
                                 nsISupports* aContainer, nsIChannel* aChannel) {
@@ -489,15 +487,13 @@ nsresult nsXMLContentSink::CreateElement(
   if (aNodeInfo->Equals(nsGkAtoms::link, kNameSpaceID_XHTML) ||
       aNodeInfo->Equals(nsGkAtoms::style, kNameSpaceID_XHTML) ||
       aNodeInfo->Equals(nsGkAtoms::style, kNameSpaceID_SVG)) {
-    nsCOMPtr<nsIStyleSheetLinkingElement> ssle(do_QueryInterface(content));
-    if (ssle) {
-      ssle->InitStyleLinkElement(false);
+    if (auto* linkStyle = LinkStyle::FromNode(*content)) {
       if (aFromParser) {
-        ssle->SetEnableUpdates(false);
+        linkStyle->SetEnableUpdates(false);
       }
       if (!aNodeInfo->Equals(nsGkAtoms::link, kNameSpaceID_XHTML)) {
-        ssle->SetLineNumber(aFromParser ? aLineNumber : 0);
-        ssle->SetColumnNumber(aFromParser ? aColumnNumber : 0);
+        linkStyle->SetLineNumber(aFromParser ? aLineNumber : 0);
+        linkStyle->SetColumnNumber(aFromParser ? aColumnNumber : 0);
       }
     }
   }
@@ -573,11 +569,10 @@ nsresult nsXMLContentSink::CloseElement(nsIContent* aContent) {
   } else if (nodeInfo->Equals(nsGkAtoms::link, kNameSpaceID_XHTML) ||
              nodeInfo->Equals(nsGkAtoms::style, kNameSpaceID_XHTML) ||
              nodeInfo->Equals(nsGkAtoms::style, kNameSpaceID_SVG)) {
-    nsCOMPtr<nsIStyleSheetLinkingElement> ssle(do_QueryInterface(aContent));
-    if (ssle) {
-      ssle->SetEnableUpdates(true);
+    if (auto* linkStyle = LinkStyle::FromNode(*aContent)) {
+      linkStyle->SetEnableUpdates(true);
       auto updateOrError =
-          ssle->UpdateStyleSheet(mRunsToCompletion ? nullptr : this);
+          linkStyle->UpdateStyleSheet(mRunsToCompletion ? nullptr : this);
       if (updateOrError.isErr()) {
         rv = updateOrError.unwrapErr();
       } else if (updateOrError.unwrap().ShouldBlock() && !mRunsToCompletion) {
@@ -633,8 +628,8 @@ nsresult nsXMLContentSink::LoadXSLStyleSheet(nsIURI* aUrl) {
 
 nsresult nsXMLContentSink::ProcessStyleLinkFromHeader(
     const nsAString& aHref, bool aAlternate, const nsAString& aTitle,
-    const nsAString& aType, const nsAString& aMedia,
-    const nsAString& aReferrerPolicy) {
+    const nsAString& aIntegrity, const nsAString& aType,
+    const nsAString& aMedia, const nsAString& aReferrerPolicy) {
   mPrettyPrintXML = false;
 
   nsAutoCString cmd;
@@ -653,7 +648,7 @@ nsresult nsXMLContentSink::ProcessStyleLinkFromHeader(
 
   // Otherwise fall through to nsContentSink to handle CSS Link headers.
   return nsContentSink::ProcessStyleLinkFromHeader(
-      aHref, aAlternate, aTitle, aType, aMedia, aReferrerPolicy);
+      aHref, aAlternate, aTitle, aIntegrity, aType, aMedia, aReferrerPolicy);
 }
 
 nsresult nsXMLContentSink::MaybeProcessXSLTLink(
@@ -1162,11 +1157,9 @@ nsXMLContentSink::HandleProcessingInstruction(const char16_t* aTarget,
   RefPtr<ProcessingInstruction> node =
       NS_NewXMLProcessingInstruction(mNodeInfoManager, target, data);
 
-  nsCOMPtr<nsIStyleSheetLinkingElement> ssle =
-      do_QueryInterface(ToSupports(node));
-  if (ssle) {
-    ssle->InitStyleLinkElement(false);
-    ssle->SetEnableUpdates(false);
+  auto* linkStyle = LinkStyle::FromNode(*node);
+  if (linkStyle) {
+    linkStyle->SetEnableUpdates(false);
     mPrettyPrintXML = false;
   }
 
@@ -1174,12 +1167,12 @@ nsXMLContentSink::HandleProcessingInstruction(const char16_t* aTarget,
   NS_ENSURE_SUCCESS(rv, rv);
   DidAddContent();
 
-  if (ssle) {
+  if (linkStyle) {
     // This is an xml-stylesheet processing instruction... but it might not be
     // a CSS one if the type is set to something else.
-    ssle->SetEnableUpdates(true);
+    linkStyle->SetEnableUpdates(true);
     auto updateOrError =
-        ssle->UpdateStyleSheet(mRunsToCompletion ? nullptr : this);
+        linkStyle->UpdateStyleSheet(mRunsToCompletion ? nullptr : this);
     if (updateOrError.isErr()) {
       return updateOrError.unwrapErr();
     }
diff --git a/dom/xml/nsXMLContentSink.h b/dom/xml/nsXMLContentSink.h
index 668154c076..cb97151574 100644
--- a/dom/xml/nsXMLContentSink.h
+++ b/dom/xml/nsXMLContentSink.h
@@ -144,8 +144,8 @@ class nsXMLContentSink : public nsContentSink,
   // nsContentSink override
   virtual nsresult ProcessStyleLinkFromHeader(
       const nsAString& aHref, bool aAlternate, const nsAString& aTitle,
-      const nsAString& aType, const nsAString& aMedia,
-      const nsAString& aReferrerPolicy) override;
+      const nsAString& aIntegrity, const nsAString& aType,
+      const nsAString& aMedia, const nsAString& aReferrerPolicy) override;
 
   // Try to handle an XSLT style link.  If NS_OK is returned and aWasXSLT is not
   // null, *aWasXSLT will be set to whether we processed this link as XSLT.
diff --git a/dom/xml/nsXMLElement.h b/dom/xml/nsXMLElement.h
index 476af83b0b..bb352caf98 100644
--- a/dom/xml/nsXMLElement.h
+++ b/dom/xml/nsXMLElement.h
@@ -24,7 +24,7 @@ class nsXMLElement : public mozilla::dom::Element {
   virtual void UnbindFromTree(bool aNullParent = true) override;
 
  protected:
-  virtual ~nsXMLElement() {}
+  virtual ~nsXMLElement() = default;
 
   virtual JSObject* WrapNode(JSContext* aCx,
                              JS::Handle<JSObject*> aGivenProto) override;
diff --git a/dom/xml/nsXMLFragmentContentSink.cpp b/dom/xml/nsXMLFragmentContentSink.cpp
index 6edcb93fba..3f1fe7b661 100644
--- a/dom/xml/nsXMLFragmentContentSink.cpp
+++ b/dom/xml/nsXMLFragmentContentSink.cpp
@@ -85,8 +85,8 @@ class nsXMLFragmentContentSink : public nsXMLContentSink,
   // nsContentSink overrides
   virtual nsresult ProcessStyleLinkFromHeader(
       const nsAString& aHref, bool aAlternate, const nsAString& aTitle,
-      const nsAString& aType, const nsAString& aMedia,
-      const nsAString& aReferrerPolicy) override;
+      const nsAString& aIntegrity, const nsAString& aType,
+      const nsAString& aMedia, const nsAString& aReferrerPolicy) override;
 
   // nsXMLContentSink overrides
   virtual nsresult MaybeProcessXSLTLink(
@@ -118,7 +118,7 @@ nsXMLFragmentContentSink::nsXMLFragmentContentSink() : mParseError(false) {
   mRunsToCompletion = true;
 }
 
-nsXMLFragmentContentSink::~nsXMLFragmentContentSink() {}
+nsXMLFragmentContentSink::~nsXMLFragmentContentSink() = default;
 
 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(nsXMLFragmentContentSink)
   NS_INTERFACE_MAP_ENTRY(nsIFragmentContentSink)
@@ -288,8 +288,8 @@ nsXMLFragmentContentSink::ReportError(const char16_t* aErrorText,
 
 nsresult nsXMLFragmentContentSink::ProcessStyleLinkFromHeader(
     const nsAString& aHref, bool aAlternate, const nsAString& aTitle,
-    const nsAString& aType, const nsAString& aMedia,
-    const nsAString& aReferrerPolicy)
+    const nsAString& aIntegrity, const nsAString& aType,
+    const nsAString& aMedia, const nsAString& aReferrerPolicy)
 
 {
   MOZ_ASSERT_UNREACHABLE("Shouldn't have headers for a fragment sink");
diff --git a/dom/xslt/base/txExpandedNameMap.h b/dom/xslt/base/txExpandedNameMap.h
index 980f11e89a..428e1a4d9a 100644
--- a/dom/xslt/base/txExpandedNameMap.h
+++ b/dom/xslt/base/txExpandedNameMap.h
@@ -5,7 +5,7 @@
 #ifndef TRANSFRMX_EXPANDEDNAMEMAP_H
 #define TRANSFRMX_EXPANDEDNAMEMAP_H
 
-#include "nsAutoPtr.h"
+#include "mozilla/UniquePtr.h"
 #include "nsError.h"
 #include "txExpandedName.h"
 #include "nsTArray.h"
@@ -124,7 +124,7 @@ class txOwningExpandedNameMap : public txExpandedNameMap_base {
   }
 
   nsresult set(const txExpandedName& aKey, E* aValue) {
-    nsAutoPtr<E> oldValue;
+    mozilla::UniquePtr<E> oldValue;
     return setItem(aKey, (void*)aValue, getter_Transfers(oldValue));
   }
 
diff --git a/dom/xslt/base/txList.cpp b/dom/xslt/base/txList.cpp
index 8aceef0cb9..91c24d1821 100644
--- a/dom/xslt/base/txList.cpp
+++ b/dom/xslt/base/txList.cpp
@@ -24,7 +24,7 @@ txList::txList() {
  */
 txList::~txList() { clear(); }  //-- ~txList
 
-nsresult txList::add(void* objPtr) { return insertBefore(objPtr, 0); }  //-- add
+void txList::add(void* objPtr) { insertBefore(objPtr, 0); }  //-- add
 
 /**
  * Returns the number of items in this txList
@@ -38,10 +38,13 @@ int32_t List::getLength() { return itemCount; }  //-- getLength
  * This method assumes refItem is a member of this list, and since this
  * is a private method, I feel that's a valid assumption
  **/
-nsresult txList::insertAfter(void* objPtr, ListItem* refItem) {
+void txList::insertAfter(void* objPtr, ListItem* refItem) {
   //-- if refItem == null insert at front
-  if (!refItem) return insertBefore(objPtr, firstItem);
-  return insertBefore(objPtr, refItem->nextItem);
+  if (!refItem) {
+    insertBefore(objPtr, firstItem);
+  } else {
+    insertBefore(objPtr, refItem->nextItem);
+  }
 }  //-- insertAfter
 
 /**
@@ -51,7 +54,7 @@ nsresult txList::insertAfter(void* objPtr, ListItem* refItem) {
  * This method assumes refItem is a member of this list, and since this
  * is a private method, I feel that's a valid assumption
  **/
-nsresult txList::insertBefore(void* objPtr, ListItem* refItem) {
+void txList::insertBefore(void* objPtr, ListItem* refItem) {
   ListItem* item = new ListItem;
   item->objPtr = objPtr;
   item->nextItem = 0;
@@ -80,8 +83,6 @@ nsresult txList::insertBefore(void* objPtr, ListItem* refItem) {
 
   // increase the item count
   ++itemCount;
-
-  return NS_OK;
 }  //-- insertBefore
 
 txList::ListItem* txList::remove(ListItem* item) {
@@ -137,11 +138,12 @@ txListIterator::txListIterator(txList* list) {
  * based on the current position within the txList
  * @param objPtr the Object pointer to add to the list
  **/
-nsresult txListIterator::addAfter(void* objPtr) {
-  if (currentItem || !atEndOfList)
-    return list->insertAfter(objPtr, currentItem);
-  return list->insertBefore(objPtr, 0);
-
+void txListIterator::addAfter(void* objPtr) {
+  if (currentItem || !atEndOfList) {
+    list->insertAfter(objPtr, currentItem);
+  } else {
+    list->insertBefore(objPtr, 0);
+  }
 }  //-- addAfter
 
 /**
@@ -150,11 +152,12 @@ nsresult txListIterator::addAfter(void* objPtr) {
  * based on the current position within the txList
  * @param objPtr the Object pointer to add to the list
  **/
-nsresult txListIterator::addBefore(void* objPtr) {
-  if (currentItem || atEndOfList)
-    return list->insertBefore(objPtr, currentItem);
-  return list->insertAfter(objPtr, 0);
-
+void txListIterator::addBefore(void* objPtr) {
+  if (currentItem || atEndOfList) {
+    list->insertBefore(objPtr, currentItem);
+  } else {
+    list->insertAfter(objPtr, 0);
+  }
 }  //-- addBefore
 
 /**
diff --git a/dom/xslt/base/txList.h b/dom/xslt/base/txList.h
index 2b88058806..feaec07ea3 100644
--- a/dom/xslt/base/txList.h
+++ b/dom/xslt/base/txList.h
@@ -39,7 +39,7 @@ class txList : public txObject {
   /**
    * Adds the given Object to the list
    **/
-  nsresult add(void* objPtr);
+  void add(void* objPtr);
 
   /*
    * Removes all the objects from the list
@@ -65,8 +65,8 @@ class txList : public txObject {
   ListItem* lastItem;
   int32_t itemCount;
 
-  nsresult insertAfter(void* objPtr, ListItem* sItem);
-  nsresult insertBefore(void* objPtr, ListItem* sItem);
+  void insertAfter(void* objPtr, ListItem* sItem);
+  void insertBefore(void* objPtr, ListItem* sItem);
 };
 
 /**
@@ -86,7 +86,7 @@ class txListIterator {
    * based on the current position within the txList
    * @param objPtr the Object pointer to add to the list
    **/
-  nsresult addAfter(void* objPtr);
+  void addAfter(void* objPtr);
 
   /**
    * Adds the Object pointer to the txList pointed to by this txListIterator.
@@ -94,7 +94,7 @@ class txListIterator {
    * based on the current position within the txList
    * @param objPtr the Object pointer to add to the list
    **/
-  nsresult addBefore(void* objPtr);
+  void addBefore(void* objPtr);
 
   /**
    * Returns true if a successful call to the next() method can be made
diff --git a/dom/xslt/crashtests/1589930.xml b/dom/xslt/crashtests/1589930.xml
new file mode 100644
index 0000000000..74d4cc8463
--- /dev/null
+++ b/dom/xslt/crashtests/1589930.xml
@@ -0,0 +1,10 @@
+<?xml version="1.0"?>
+<?xml-stylesheet type="text/xsl" href="#stylesheet"?>
+<!DOCTYPE root [
+  <!ATTLIST xsl:stylesheet id ID #IMPLIED>
+]>
+<root>
+<xsl:stylesheet id="stylesheet" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
+  <xsl:template match="/"><xsl:value-of select="format-number(99.98, '0.0')"/></xsl:template>
+</xsl:stylesheet>
+</root>
diff --git a/dom/xslt/crashtests/crashtests.list b/dom/xslt/crashtests/crashtests.list
index bef3f78e77..711f357862 100644
--- a/dom/xslt/crashtests/crashtests.list
+++ b/dom/xslt/crashtests/crashtests.list
@@ -26,4 +26,5 @@ load 1336832.html
 load 1338277.html
 load 1361892.html
 load 1527277.html
+load 1589930.xml
 HTTP load 1430818.sjs
diff --git a/dom/xslt/xpath/XPathEvaluator.cpp b/dom/xslt/xpath/XPathEvaluator.cpp
index 50341ea571..0aa3eba4b7 100644
--- a/dom/xslt/xpath/XPathEvaluator.cpp
+++ b/dom/xslt/xpath/XPathEvaluator.cpp
@@ -3,24 +3,26 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "mozilla/dom/XPathEvaluator.h"
-#include "mozilla/Move.h"
-#include "nsCOMPtr.h"
-#include "nsAtom.h"
-#include "mozilla/dom/XPathExpression.h"
+
+#include <utility>
+
 #include "XPathResult.h"
-#include "nsContentCID.h"
-#include "txExpr.h"
-#include "txExprParser.h"
-#include "nsError.h"
-#include "txURIUtils.h"
+#include "mozilla/dom/BindingUtils.h"
 #include "mozilla/dom/Document.h"
+#include "mozilla/dom/XPathEvaluatorBinding.h"
+#include "mozilla/dom/XPathExpression.h"
+#include "mozilla/dom/XPathNSResolverBinding.h"
+#include "nsAtom.h"
+#include "nsCOMPtr.h"
+#include "nsContentCID.h"
+#include "nsContentUtils.h"
 #include "nsDOMString.h"
+#include "nsError.h"
 #include "nsNameSpaceManager.h"
-#include "nsContentUtils.h"
+#include "txExpr.h"
+#include "txExprParser.h"
 #include "txIXPathContext.h"
-#include "mozilla/dom/XPathEvaluatorBinding.h"
-#include "mozilla/dom/BindingUtils.h"
-#include "mozilla/dom/XPathNSResolverBinding.h"
+#include "txURIUtils.h"
 
 namespace mozilla {
 namespace dom {
@@ -85,7 +87,7 @@ XPathExpression* XPathEvaluator::CreateExpression(const nsAString& aExpression,
     mRecycler = new txResultRecycler;
   }
 
-  nsAutoPtr<Expr> expression;
+  UniquePtr<Expr> expression;
   aRv = txExprParser::createExpr(PromiseFlatString(aExpression), aContext,
                                  getter_Transfers(expression));
   if (aRv.Failed()) {
@@ -115,7 +117,7 @@ already_AddRefed<XPathResult> XPathEvaluator::Evaluate(
     JSContext* aCx, const nsAString& aExpression, nsINode& aContextNode,
     XPathNSResolver* aResolver, uint16_t aType, JS::Handle<JSObject*> aResult,
     ErrorResult& rv) {
-  nsAutoPtr<XPathExpression> expression(
+  UniquePtr<XPathExpression> expression(
       CreateExpression(aExpression, aResolver, rv));
   if (rv.Failed()) {
     return nullptr;
diff --git a/dom/xslt/xpath/XPathEvaluator.h b/dom/xslt/xpath/XPathEvaluator.h
index 10071aaf80..e843734888 100644
--- a/dom/xslt/xpath/XPathEvaluator.h
+++ b/dom/xslt/xpath/XPathEvaluator.h
@@ -6,7 +6,6 @@
 #define mozilla_dom_XPathEvaluator_h
 
 #include "mozilla/dom/NonRefcountedDOMObject.h"
-#include "nsAutoPtr.h"
 #include "nsString.h"
 #include "mozilla/Attributes.h"
 #include "mozilla/ErrorResult.h"
diff --git a/dom/xslt/xpath/XPathExpression.cpp b/dom/xslt/xpath/XPathExpression.cpp
index 0a093f7854..4746c11251 100644
--- a/dom/xslt/xpath/XPathExpression.cpp
+++ b/dom/xslt/xpath/XPathExpression.cpp
@@ -2,19 +2,21 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-#include "mozilla/Move.h"
 #include "XPathExpression.h"
+
+#include <utility>
+
+#include "XPathResult.h"
+#include "mozilla/dom/BindingUtils.h"
+#include "mozilla/dom/Text.h"
+#include "mozilla/dom/XPathResultBinding.h"
+#include "nsError.h"
+#include "nsINode.h"
 #include "txExpr.h"
 #include "txExprResult.h"
 #include "txIXPathContext.h"
-#include "nsError.h"
-#include "nsINode.h"
-#include "XPathResult.h"
 #include "txURIUtils.h"
 #include "txXPathTreeWalker.h"
-#include "mozilla/dom/BindingUtils.h"
-#include "mozilla/dom/Text.h"
-#include "mozilla/dom/XPathResultBinding.h"
 
 namespace mozilla {
 namespace dom {
@@ -41,7 +43,7 @@ class EvalContextImpl : public txIEvalContext {
   RefPtr<txResultRecycler> mRecycler;
 };
 
-XPathExpression::XPathExpression(nsAutoPtr<Expr>&& aExpression,
+XPathExpression::XPathExpression(UniquePtr<Expr>&& aExpression,
                                  txResultRecycler* aRecycler,
                                  Document* aDocument)
     : mExpression(std::move(aExpression)),
@@ -119,7 +121,7 @@ already_AddRefed<XPathResult> XPathExpression::EvaluateWithContext(
     return nullptr;
   }
 
-  nsAutoPtr<txXPathNode> contextNode(
+  UniquePtr<txXPathNode> contextNode(
       txXPathNativeNode::createXPathNode(&aContextNode));
   if (!contextNode) {
     aRv.Throw(NS_ERROR_FAILURE);
diff --git a/dom/xslt/xpath/XPathExpression.h b/dom/xslt/xpath/XPathExpression.h
index f964535fa6..0169dda37e 100644
--- a/dom/xslt/xpath/XPathExpression.h
+++ b/dom/xslt/xpath/XPathExpression.h
@@ -5,12 +5,12 @@
 #ifndef mozilla_dom_XPathExpression_h
 #define mozilla_dom_XPathExpression_h
 
-#include "nsAutoPtr.h"
 #include "nsCycleCollectionParticipant.h"
 #include "nsIWeakReferenceUtils.h"
 #include "mozilla/Attributes.h"
 #include "mozilla/dom/NonRefcountedDOMObject.h"
 #include "mozilla/dom/XPathExpressionBinding.h"
+#include "mozilla/UniquePtr.h"
 
 class Expr;
 
@@ -20,6 +20,7 @@ class txResultRecycler;
 namespace mozilla {
 namespace dom {
 
+class Document;
 class XPathResult;
 
 /**
@@ -27,8 +28,8 @@ class XPathResult;
  */
 class XPathExpression final : public NonRefcountedDOMObject {
  public:
-  XPathExpression(nsAutoPtr<Expr>&& aExpression, txResultRecycler* aRecycler,
-                  Document* aDocument);
+  XPathExpression(mozilla::UniquePtr<Expr>&& aExpression,
+                  txResultRecycler* aRecycler, Document* aDocument);
   ~XPathExpression();
 
   bool WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto,
@@ -56,7 +57,7 @@ class XPathExpression final : public NonRefcountedDOMObject {
       uint16_t aType, XPathResult* aInResult, ErrorResult& aRv);
 
  private:
-  nsAutoPtr<Expr> mExpression;
+  mozilla::UniquePtr<Expr> mExpression;
   RefPtr<txResultRecycler> mRecycler;
   nsWeakPtr mDocument;
   bool mCheckDocument;
diff --git a/dom/xslt/xpath/XPathResult.cpp b/dom/xslt/xpath/XPathResult.cpp
index 60a45d7ed2..84f08dac72 100644
--- a/dom/xslt/xpath/XPathResult.cpp
+++ b/dom/xslt/xpath/XPathResult.cpp
@@ -252,7 +252,7 @@ nsresult XPathResult::GetExprResult(txAExprResult** aExprResult) {
 
   uint32_t i, count = mResultNodes.Count();
   for (i = 0; i < count; ++i) {
-    nsAutoPtr<txXPathNode> node(
+    UniquePtr<txXPathNode> node(
         txXPathNativeNode::createXPathNode(mResultNodes[i]));
     if (!node) {
       return NS_ERROR_OUT_OF_MEMORY;
diff --git a/dom/xslt/xpath/XPathResult.h b/dom/xslt/xpath/XPathResult.h
index 67027cf350..52212efbb0 100644
--- a/dom/xslt/xpath/XPathResult.h
+++ b/dom/xslt/xpath/XPathResult.h
@@ -6,7 +6,6 @@
 #define mozilla_dom_XPathResult_h
 
 #include "nsStubMutationObserver.h"
-#include "nsAutoPtr.h"
 #include "nsCOMPtr.h"
 #include "nsCOMArray.h"
 #include "nsIWeakReferenceUtils.h"
diff --git a/dom/xslt/xpath/txCoreFunctionCall.cpp b/dom/xslt/xpath/txCoreFunctionCall.cpp
index 9842ed515b..c034be73be 100644
--- a/dom/xslt/xpath/txCoreFunctionCall.cpp
+++ b/dom/xslt/xpath/txCoreFunctionCall.cpp
@@ -6,7 +6,6 @@
 #include "mozilla/FloatingPoint.h"
 
 #include "txExpr.h"
-#include "nsAutoPtr.h"
 #include "txNodeSet.h"
 #include "nsGkAtoms.h"
 #include "txIXPathContext.h"
diff --git a/dom/xslt/xpath/txExpr.h b/dom/xslt/xpath/txExpr.h
index 26f6ae66ae..0a4722272d 100644
--- a/dom/xslt/xpath/txExpr.h
+++ b/dom/xslt/xpath/txExpr.h
@@ -6,7 +6,7 @@
 #define TRANSFRMX_EXPR_H
 
 #include "mozilla/Attributes.h"
-#include "nsAutoPtr.h"
+#include "mozilla/UniquePtr.h"
 #include "txExprResult.h"
 #include "txCore.h"
 #include "nsString.h"
@@ -165,14 +165,14 @@ class Expr {
   TX_IMPL_EXPR_STUBS_BASE(_class, _ReturnType)                 \
   Expr* _class::getSubExprAt(uint32_t aPos) {                  \
     if (aPos == 0) {                                           \
-      return _Expr1;                                           \
+      return _Expr1.get();                                     \
     }                                                          \
     return nullptr;                                            \
   }                                                            \
   void _class::setSubExprAt(uint32_t aPos, Expr* aExpr) {      \
     NS_ASSERTION(aPos < 1, "setting bad subexpression index"); \
-    _Expr1.forget();                                           \
-    _Expr1 = aExpr;                                            \
+    mozilla::Unused << _Expr1.release();                       \
+    _Expr1 = mozilla::WrapUnique(aExpr);                       \
   }
 
 #define TX_IMPL_EXPR_STUBS_2(_class, _ReturnType, _Expr1, _Expr2) \
@@ -180,9 +180,9 @@ class Expr {
   Expr* _class::getSubExprAt(uint32_t aPos) {                     \
     switch (aPos) {                                               \
       case 0:                                                     \
-        return _Expr1;                                            \
+        return _Expr1.get();                                      \
       case 1:                                                     \
-        return _Expr2;                                            \
+        return _Expr2.get();                                      \
       default:                                                    \
         break;                                                    \
     }                                                             \
@@ -191,11 +191,11 @@ class Expr {
   void _class::setSubExprAt(uint32_t aPos, Expr* aExpr) {         \
     NS_ASSERTION(aPos < 2, "setting bad subexpression index");    \
     if (aPos == 0) {                                              \
-      _Expr1.forget();                                            \
-      _Expr1 = aExpr;                                             \
+      mozilla::Unused << _Expr1.release();                        \
+      _Expr1 = mozilla::WrapUnique(aExpr);                        \
     } else {                                                      \
-      _Expr2.forget();                                            \
-      _Expr2 = aExpr;                                             \
+      mozilla::Unused << _Expr2.release();                        \
+      _Expr2 = mozilla::WrapUnique(aExpr);                        \
     }                                                             \
   }
 
@@ -431,8 +431,8 @@ class txPredicatedNodeTest : public txNodeTest {
   TX_DECL_NODE_TEST
 
  private:
-  nsAutoPtr<txNodeTest> mNodeTest;
-  nsAutoPtr<Expr> mPredicate;
+  mozilla::UniquePtr<txNodeTest> mNodeTest;
+  mozilla::UniquePtr<Expr> mPredicate;
 };
 
 /**
@@ -521,10 +521,10 @@ class LocationStep : public Expr, public PredicateList {
 
   TX_DECL_OPTIMIZABLE_EXPR
 
-  txNodeTest* getNodeTest() { return mNodeTest; }
+  txNodeTest* getNodeTest() { return mNodeTest.get(); }
   void setNodeTest(txNodeTest* aNodeTest) {
-    mNodeTest.forget();
-    mNodeTest = aNodeTest;
+    mozilla::Unused << mNodeTest.release();
+    mNodeTest = mozilla::WrapUnique(aNodeTest);
   }
   LocationStepType getAxisIdentifier() { return mAxisIdentifier; }
   void setAxisIdentifier(LocationStepType aAxisIdentifier) {
@@ -556,7 +556,7 @@ class LocationStep : public Expr, public PredicateList {
                                         txIMatchContext* aContext,
                                         txNodeSet* aNodes);
 
-  nsAutoPtr<txNodeTest> mNodeTest;
+  mozilla::UniquePtr<txNodeTest> mNodeTest;
   LocationStepType mAxisIdentifier;
 };
 
@@ -571,7 +571,7 @@ class FilterExpr : public Expr, public PredicateList {
   TX_DECL_EXPR
 
  private:
-  nsAutoPtr<Expr> expr;
+  mozilla::UniquePtr<Expr> expr;
 
 };  //-- FilterExpr
 
@@ -599,7 +599,7 @@ class UnaryExpr : public Expr {
   TX_DECL_EXPR
 
  private:
-  nsAutoPtr<Expr> expr;
+  mozilla::UniquePtr<Expr> expr;
 };  //-- UnaryExpr
 
 /**
@@ -617,7 +617,7 @@ class BooleanExpr : public Expr {
   TX_DECL_EXPR
 
  private:
-  nsAutoPtr<Expr> leftExpr, rightExpr;
+  mozilla::UniquePtr<Expr> leftExpr, rightExpr;
   short op;
 };  //-- BooleanExpr
 
@@ -639,7 +639,7 @@ class txNumberExpr : public Expr {
   TX_DECL_EXPR
 
  private:
-  nsAutoPtr<Expr> mLeftExpr, mRightExpr;
+  mozilla::UniquePtr<Expr> mLeftExpr, mRightExpr;
   eOp mOp;
 };  //-- MultiplicativeExpr
 
@@ -673,8 +673,8 @@ class RelationalExpr : public Expr {
   bool compareResults(txIEvalContext* aContext, txAExprResult* aLeft,
                       txAExprResult* aRight);
 
-  nsAutoPtr<Expr> mLeftExpr;
-  nsAutoPtr<Expr> mRightExpr;
+  mozilla::UniquePtr<Expr> mLeftExpr;
+  mozilla::UniquePtr<Expr> mRightExpr;
   RelationalExprType mOp;
 };
 
@@ -735,7 +735,7 @@ class PathExpr : public Expr {
  private:
   class PathExprItem {
    public:
-    nsAutoPtr<Expr> expr;
+    mozilla::UniquePtr<Expr> expr;
     PathOperator pathOp;
   };
 
diff --git a/dom/xslt/xpath/txExprParser.cpp b/dom/xslt/xpath/txExprParser.cpp
index 04f0fec02b..8499c97f98 100644
--- a/dom/xslt/xpath/txExprParser.cpp
+++ b/dom/xslt/xpath/txExprParser.cpp
@@ -8,18 +8,25 @@
  * @see ExprLexer
  **/
 
-#include "mozilla/Move.h"
 #include "txExprParser.h"
-#include "txExprLexer.h"
-#include "txExpr.h"
-#include "txStack.h"
-#include "nsGkAtoms.h"
+
+#include <utility>
+
 #include "nsError.h"
+#include "nsGkAtoms.h"
+#include "txExpr.h"
+#include "txExprLexer.h"
 #include "txIXPathContext.h"
+#include "txStack.h"
 #include "txStringUtils.h"
 #include "txXPathNode.h"
 #include "txXPathOptimizer.h"
 
+using mozilla::MakeUnique;
+using mozilla::UniquePtr;
+using mozilla::Unused;
+using mozilla::WrapUnique;
+
 /**
  * Creates an Attribute Value Template using the given value
  * This should move to XSLProcessor class
@@ -28,7 +35,7 @@ nsresult txExprParser::createAVT(const nsAString& aAttrValue,
                                  txIParseContext* aContext, Expr** aResult) {
   *aResult = nullptr;
   nsresult rv = NS_OK;
-  nsAutoPtr<Expr> expr;
+  UniquePtr<Expr> expr;
   FunctionCall* concat = nullptr;
 
   nsAutoString literalString;
@@ -42,7 +49,7 @@ nsresult txExprParser::createAVT(const nsAString& aAttrValue,
     // Every iteration through this loop parses either a literal section
     // or an expression
     start = iter;
-    nsAutoPtr<Expr> newExpr;
+    UniquePtr<Expr> newExpr;
     if (!inExpr) {
       // Parse literal section
       literalString.Truncate();
@@ -75,7 +82,8 @@ nsresult txExprParser::createAVT(const nsAString& aAttrValue,
         // Restart the loop since we didn't create an expression
         continue;
       }
-      newExpr = new txLiteralExpr(literalString + Substring(start, iter));
+      newExpr =
+          MakeUnique<txLiteralExpr>(literalString + Substring(start, iter));
     } else {
       // Parse expressions, iter is already past the initial '{' when
       // we get here.
@@ -111,12 +119,12 @@ nsresult txExprParser::createAVT(const nsAString& aAttrValue,
     } else {
       if (!concat) {
         concat = new txCoreFunctionCall(txCoreFunctionCall::CONCAT);
-        rv = concat->addParam(expr.forget());
-        expr = concat;
+        rv = concat->addParam(expr.release());
+        expr = WrapUnique(concat);
         NS_ENSURE_SUCCESS(rv, rv);
       }
 
-      rv = concat->addParam(newExpr.forget());
+      rv = concat->addParam(newExpr.release());
       NS_ENSURE_SUCCESS(rv, rv);
     }
   }
@@ -127,10 +135,10 @@ nsresult txExprParser::createAVT(const nsAString& aAttrValue,
   }
 
   if (!expr) {
-    expr = new txLiteralExpr(EmptyString());
+    expr = MakeUnique<txLiteralExpr>(EmptyString());
   }
 
-  *aResult = expr.forget();
+  *aResult = expr.release();
 
   return NS_OK;
 }
@@ -149,7 +157,7 @@ nsresult txExprParser::createExprInternal(const nsAString& aExpression,
     aContext->SetErrorOffset(lexer.mPosition - start + aSubStringPos);
     return rv;
   }
-  nsAutoPtr<Expr> expr;
+  UniquePtr<Expr> expr;
   rv = createExpr(lexer, aContext, getter_Transfers(expr));
   if (NS_SUCCEEDED(rv) && lexer.peek()->mType != Token::END) {
     rv = NS_ERROR_XPATH_BINARY_EXPECTED;
@@ -164,10 +172,10 @@ nsresult txExprParser::createExprInternal(const nsAString& aExpression,
 
   txXPathOptimizer optimizer;
   Expr* newExpr = nullptr;
-  rv = optimizer.optimize(expr, &newExpr);
+  rv = optimizer.optimize(expr.get(), &newExpr);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  *aExpr = newExpr ? newExpr : expr.forget();
+  *aExpr = newExpr ? newExpr : expr.release();
 
   return NS_OK;
 }
@@ -179,8 +187,8 @@ nsresult txExprParser::createExprInternal(const nsAString& aExpression,
 /**
  * Creates a binary Expr for the given operator
  */
-nsresult txExprParser::createBinaryExpr(nsAutoPtr<Expr>& left,
-                                        nsAutoPtr<Expr>& right, Token* op,
+nsresult txExprParser::createBinaryExpr(UniquePtr<Expr>& left,
+                                        UniquePtr<Expr>& right, Token* op,
                                         Expr** aResult) {
   NS_ASSERTION(op, "internal error");
   *aResult = nullptr;
@@ -189,49 +197,54 @@ nsresult txExprParser::createBinaryExpr(nsAutoPtr<Expr>& left,
   switch (op->mType) {
     //-- math ops
     case Token::ADDITION_OP:
-      expr = new txNumberExpr(left, right, txNumberExpr::ADD);
+      expr = new txNumberExpr(left.get(), right.get(), txNumberExpr::ADD);
       break;
     case Token::SUBTRACTION_OP:
-      expr = new txNumberExpr(left, right, txNumberExpr::SUBTRACT);
+      expr = new txNumberExpr(left.get(), right.get(), txNumberExpr::SUBTRACT);
       break;
     case Token::DIVIDE_OP:
-      expr = new txNumberExpr(left, right, txNumberExpr::DIVIDE);
+      expr = new txNumberExpr(left.get(), right.get(), txNumberExpr::DIVIDE);
       break;
     case Token::MODULUS_OP:
-      expr = new txNumberExpr(left, right, txNumberExpr::MODULUS);
+      expr = new txNumberExpr(left.get(), right.get(), txNumberExpr::MODULUS);
       break;
     case Token::MULTIPLY_OP:
-      expr = new txNumberExpr(left, right, txNumberExpr::MULTIPLY);
+      expr = new txNumberExpr(left.get(), right.get(), txNumberExpr::MULTIPLY);
       break;
 
     //-- case boolean ops
     case Token::AND_OP:
-      expr = new BooleanExpr(left, right, BooleanExpr::AND);
+      expr = new BooleanExpr(left.get(), right.get(), BooleanExpr::AND);
       break;
     case Token::OR_OP:
-      expr = new BooleanExpr(left, right, BooleanExpr::OR);
+      expr = new BooleanExpr(left.get(), right.get(), BooleanExpr::OR);
       break;
 
     //-- equality ops
     case Token::EQUAL_OP:
-      expr = new RelationalExpr(left, right, RelationalExpr::EQUAL);
+      expr = new RelationalExpr(left.get(), right.get(), RelationalExpr::EQUAL);
       break;
     case Token::NOT_EQUAL_OP:
-      expr = new RelationalExpr(left, right, RelationalExpr::NOT_EQUAL);
+      expr = new RelationalExpr(left.get(), right.get(),
+                                RelationalExpr::NOT_EQUAL);
       break;
 
     //-- relational ops
     case Token::LESS_THAN_OP:
-      expr = new RelationalExpr(left, right, RelationalExpr::LESS_THAN);
+      expr = new RelationalExpr(left.get(), right.get(),
+                                RelationalExpr::LESS_THAN);
       break;
     case Token::GREATER_THAN_OP:
-      expr = new RelationalExpr(left, right, RelationalExpr::GREATER_THAN);
+      expr = new RelationalExpr(left.get(), right.get(),
+                                RelationalExpr::GREATER_THAN);
       break;
     case Token::LESS_OR_EQUAL_OP:
-      expr = new RelationalExpr(left, right, RelationalExpr::LESS_OR_EQUAL);
+      expr = new RelationalExpr(left.get(), right.get(),
+                                RelationalExpr::LESS_OR_EQUAL);
       break;
     case Token::GREATER_OR_EQUAL_OP:
-      expr = new RelationalExpr(left, right, RelationalExpr::GREATER_OR_EQUAL);
+      expr = new RelationalExpr(left.get(), right.get(),
+                                RelationalExpr::GREATER_OR_EQUAL);
       break;
 
     default:
@@ -240,8 +253,8 @@ nsresult txExprParser::createBinaryExpr(nsAutoPtr<Expr>& left,
   }
   NS_ENSURE_TRUE(expr, NS_ERROR_OUT_OF_MEMORY);
 
-  left.forget();
-  right.forget();
+  Unused << left.release();
+  Unused << right.release();
 
   *aResult = expr;
   return NS_OK;
@@ -254,7 +267,7 @@ nsresult txExprParser::createExpr(txExprLexer& lexer, txIParseContext* aContext,
   nsresult rv = NS_OK;
   bool done = false;
 
-  nsAutoPtr<Expr> expr;
+  UniquePtr<Expr> expr;
 
   txStack exprs;
   txStack ops;
@@ -276,12 +289,12 @@ nsresult txExprParser::createExpr(txExprLexer& lexer, txIParseContext* aContext,
         FunctionCall* fcExpr =
             new txCoreFunctionCall(txCoreFunctionCall::NUMBER);
 
-        rv = fcExpr->addParam(expr);
+        rv = fcExpr->addParam(expr.get());
         if (NS_FAILED(rv)) return rv;
-        expr.forget();
-        expr = fcExpr;
+        Unused << expr.release();
+        expr = WrapUnique(fcExpr);
       } else {
-        expr = new UnaryExpr(expr.forget());
+        expr = MakeUnique<UnaryExpr>(expr.release());
       }
     }
 
@@ -291,8 +304,8 @@ nsresult txExprParser::createExpr(txExprLexer& lexer, txIParseContext* aContext,
       while (!exprs.isEmpty() &&
              tokPrecedence <= precedence(static_cast<Token*>(ops.peek()))) {
         // can't use expr as argument due to order of evaluation
-        nsAutoPtr<Expr> left(static_cast<Expr*>(exprs.pop()));
-        nsAutoPtr<Expr> right(std::move(expr));
+        UniquePtr<Expr> left(static_cast<Expr*>(exprs.pop()));
+        UniquePtr<Expr> right(std::move(expr));
         rv = createBinaryExpr(left, right, static_cast<Token*>(ops.pop()),
                               getter_Transfers(expr));
         if (NS_FAILED(rv)) {
@@ -300,7 +313,7 @@ nsresult txExprParser::createExpr(txExprLexer& lexer, txIParseContext* aContext,
           break;
         }
       }
-      exprs.push(expr.forget());
+      exprs.push(expr.release());
       ops.push(tok);
     } else {
       done = true;
@@ -308,8 +321,8 @@ nsresult txExprParser::createExpr(txExprLexer& lexer, txIParseContext* aContext,
   }
 
   while (NS_SUCCEEDED(rv) && !exprs.isEmpty()) {
-    nsAutoPtr<Expr> left(static_cast<Expr*>(exprs.pop()));
-    nsAutoPtr<Expr> right(std::move(expr));
+    UniquePtr<Expr> left(static_cast<Expr*>(exprs.pop()));
+    UniquePtr<Expr> right(std::move(expr));
     rv = createBinaryExpr(left, right, static_cast<Token*>(ops.pop()),
                           getter_Transfers(expr));
   }
@@ -319,7 +332,7 @@ nsresult txExprParser::createExpr(txExprLexer& lexer, txIParseContext* aContext,
   }
   NS_ENSURE_SUCCESS(rv, rv);
 
-  *aResult = expr.forget();
+  *aResult = expr.release();
   return NS_OK;
 }
 
@@ -331,7 +344,7 @@ nsresult txExprParser::createFilterOrStep(txExprLexer& lexer,
   nsresult rv = NS_OK;
   Token* tok = lexer.peek();
 
-  nsAutoPtr<Expr> expr;
+  UniquePtr<Expr> expr;
   switch (tok->mType) {
     case Token::FUNCTION_NAME_AND_PAREN:
       rv = createFunctionCall(lexer, aContext, getter_Transfers(expr));
@@ -345,7 +358,7 @@ nsresult txExprParser::createFilterOrStep(txExprLexer& lexer,
         nsresult rv = resolveQName(tok->Value(), getter_AddRefs(prefix),
                                    aContext, getter_AddRefs(lName), nspace);
         NS_ENSURE_SUCCESS(rv, rv);
-        expr = new VariableRefExpr(prefix, lName, nspace);
+        expr = MakeUnique<VariableRefExpr>(prefix, lName, nspace);
       }
       break;
     case Token::L_PAREN:
@@ -360,11 +373,11 @@ nsresult txExprParser::createFilterOrStep(txExprLexer& lexer,
       break;
     case Token::LITERAL:
       lexer.nextToken();
-      expr = new txLiteralExpr(tok->Value());
+      expr = MakeUnique<txLiteralExpr>(tok->Value());
       break;
     case Token::NUMBER: {
       lexer.nextToken();
-      expr = new txLiteralExpr(txDouble::toDouble(tok->Value()));
+      expr = MakeUnique<txLiteralExpr>(txDouble::toDouble(tok->Value()));
       break;
     }
     default:
@@ -372,17 +385,17 @@ nsresult txExprParser::createFilterOrStep(txExprLexer& lexer,
   }
 
   if (lexer.peek()->mType == Token::L_BRACKET) {
-    nsAutoPtr<FilterExpr> filterExpr(new FilterExpr(expr));
+    UniquePtr<FilterExpr> filterExpr(new FilterExpr(expr.get()));
 
-    expr.forget();
+    Unused << expr.release();
 
     //-- handle predicates
-    rv = parsePredicates(filterExpr, lexer, aContext);
+    rv = parsePredicates(filterExpr.get(), lexer, aContext);
     NS_ENSURE_SUCCESS(rv, rv);
-    expr = filterExpr.forget();
+    expr = std::move(filterExpr);
   }
 
-  *aResult = expr.forget();
+  *aResult = expr.release();
   return NS_OK;
 }
 
@@ -391,7 +404,7 @@ nsresult txExprParser::createFunctionCall(txExprLexer& lexer,
                                           Expr** aResult) {
   *aResult = nullptr;
 
-  nsAutoPtr<FunctionCall> fnCall;
+  UniquePtr<FunctionCall> fnCall;
 
   Token* tok = lexer.nextToken();
   NS_ASSERTION(tok->mType == Token::FUNCTION_NAME_AND_PAREN,
@@ -408,7 +421,7 @@ nsresult txExprParser::createFunctionCall(txExprLexer& lexer,
   if (namespaceID == kNameSpaceID_None &&
       txCoreFunctionCall::getTypeFromAtom(lName, type)) {
     // It is a known built-in function.
-    fnCall = new txCoreFunctionCall(type);
+    fnCall = MakeUnique<txCoreFunctionCall>(type);
   }
 
   // check extension functions and xslt
@@ -432,10 +445,10 @@ nsresult txExprParser::createFunctionCall(txExprLexer& lexer,
   }
 
   //-- handle parametes
-  rv = parseParameters(fnCall, lexer, aContext);
+  rv = parseParameters(fnCall.get(), lexer, aContext);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  *aResult = fnCall.forget();
+  *aResult = fnCall.release();
   return NS_OK;
 }
 
@@ -446,7 +459,7 @@ nsresult txExprParser::createLocationStep(txExprLexer& lexer,
 
   //-- child axis is default
   LocationStep::LocationStepType axisIdentifier = LocationStep::CHILD_AXIS;
-  nsAutoPtr<txNodeTest> nodeTest;
+  UniquePtr<txNodeTest> nodeTest;
 
   //-- get Axis Identifier or AbbreviatedStep, if present
   Token* tok = lexer.peek();
@@ -495,13 +508,13 @@ nsresult txExprParser::createLocationStep(txExprLexer& lexer,
       //-- eat token
       lexer.nextToken();
       axisIdentifier = LocationStep::PARENT_AXIS;
-      nodeTest = new txNodeTypeTest(txNodeTypeTest::NODE_TYPE);
+      nodeTest = MakeUnique<txNodeTypeTest>(txNodeTypeTest::NODE_TYPE);
       break;
     case Token::SELF_NODE:
       //-- eat token
       lexer.nextToken();
       axisIdentifier = LocationStep::SELF_AXIS;
-      nodeTest = new txNodeTypeTest(txNodeTypeTest::NODE_TYPE);
+      nodeTest = MakeUnique<txNodeTypeTest>(txNodeTypeTest::NODE_TYPE);
       break;
     default:
       break;
@@ -521,7 +534,7 @@ nsresult txExprParser::createLocationStep(txExprLexer& lexer,
                         getter_AddRefs(lName), nspace, true);
       NS_ENSURE_SUCCESS(rv, rv);
 
-      nodeTest = new txNameTest(
+      nodeTest = MakeUnique<txNameTest>(
           prefix, lName, nspace,
           axisIdentifier == LocationStep::ATTRIBUTE_AXIS
               ? static_cast<uint16_t>(txXPathNodeType::ATTRIBUTE_NODE)
@@ -532,15 +545,16 @@ nsresult txExprParser::createLocationStep(txExprLexer& lexer,
     }
   }
 
-  nsAutoPtr<LocationStep> lstep(new LocationStep(nodeTest, axisIdentifier));
+  UniquePtr<LocationStep> lstep(
+      new LocationStep(nodeTest.get(), axisIdentifier));
 
-  nodeTest.forget();
+  Unused << nodeTest.release();
 
   //-- handle predicates
-  rv = parsePredicates(lstep, lexer, aContext);
+  rv = parsePredicates(lstep.get(), lexer, aContext);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  *aExpr = lstep.forget();
+  *aExpr = lstep.release();
   return NS_OK;
 }
 
@@ -551,26 +565,26 @@ nsresult txExprParser::createLocationStep(txExprLexer& lexer,
 nsresult txExprParser::createNodeTypeTest(txExprLexer& lexer,
                                           txNodeTest** aTest) {
   *aTest = 0;
-  nsAutoPtr<txNodeTypeTest> nodeTest;
+  UniquePtr<txNodeTypeTest> nodeTest;
 
   Token* nodeTok = lexer.peek();
 
   switch (nodeTok->mType) {
     case Token::COMMENT_AND_PAREN:
       lexer.nextToken();
-      nodeTest = new txNodeTypeTest(txNodeTypeTest::COMMENT_TYPE);
+      nodeTest = MakeUnique<txNodeTypeTest>(txNodeTypeTest::COMMENT_TYPE);
       break;
     case Token::NODE_AND_PAREN:
       lexer.nextToken();
-      nodeTest = new txNodeTypeTest(txNodeTypeTest::NODE_TYPE);
+      nodeTest = MakeUnique<txNodeTypeTest>(txNodeTypeTest::NODE_TYPE);
       break;
     case Token::PROC_INST_AND_PAREN:
       lexer.nextToken();
-      nodeTest = new txNodeTypeTest(txNodeTypeTest::PI_TYPE);
+      nodeTest = MakeUnique<txNodeTypeTest>(txNodeTypeTest::PI_TYPE);
       break;
     case Token::TEXT_AND_PAREN:
       lexer.nextToken();
-      nodeTest = new txNodeTypeTest(txNodeTypeTest::TEXT_TYPE);
+      nodeTest = MakeUnique<txNodeTypeTest>(txNodeTypeTest::TEXT_TYPE);
       break;
     default:
       return NS_ERROR_XPATH_NO_NODE_TYPE_TEST;
@@ -588,7 +602,7 @@ nsresult txExprParser::createNodeTypeTest(txExprLexer& lexer,
   }
   lexer.nextToken();
 
-  *aTest = nodeTest.forget();
+  *aTest = nodeTest.release();
   return NS_OK;
 }
 
@@ -601,7 +615,7 @@ nsresult txExprParser::createPathExpr(txExprLexer& lexer,
                                       Expr** aResult) {
   *aResult = nullptr;
 
-  nsAutoPtr<Expr> expr;
+  UniquePtr<Expr> expr;
 
   Token* tok = lexer.peek();
 
@@ -623,11 +637,11 @@ nsresult txExprParser::createPathExpr(txExprLexer& lexer,
     // is this a singlestep path expression?
     tok = lexer.peek();
     if (tok->mType != Token::PARENT_OP && tok->mType != Token::ANCESTOR_OP) {
-      *aResult = expr.forget();
+      *aResult = expr.release();
       return NS_OK;
     }
   } else {
-    expr = new RootExpr();
+    expr = MakeUnique<RootExpr>();
 
 #ifdef TX_TO_STRING
     static_cast<RootExpr*>(expr.get())->setSerialize(false);
@@ -635,12 +649,12 @@ nsresult txExprParser::createPathExpr(txExprLexer& lexer,
   }
 
   // We have a PathExpr containing several steps
-  nsAutoPtr<PathExpr> pathExpr(new PathExpr());
+  UniquePtr<PathExpr> pathExpr(new PathExpr());
 
-  rv = pathExpr->addExpr(expr, PathExpr::RELATIVE_OP);
+  rv = pathExpr->addExpr(expr.get(), PathExpr::RELATIVE_OP);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  expr.forget();
+  Unused << expr.release();
 
   // this is ugly
   while (1) {
@@ -653,7 +667,7 @@ nsresult txExprParser::createPathExpr(txExprLexer& lexer,
         pathOp = PathExpr::RELATIVE_OP;
         break;
       default:
-        *aResult = pathExpr.forget();
+        *aResult = pathExpr.release();
         return NS_OK;
     }
     lexer.nextToken();
@@ -661,10 +675,10 @@ nsresult txExprParser::createPathExpr(txExprLexer& lexer,
     rv = createLocationStep(lexer, aContext, getter_Transfers(expr));
     NS_ENSURE_SUCCESS(rv, rv);
 
-    rv = pathExpr->addExpr(expr, pathOp);
+    rv = pathExpr->addExpr(expr.get(), pathOp);
     NS_ENSURE_SUCCESS(rv, rv);
 
-    expr.forget();
+    Unused << expr.release();
   }
   MOZ_ASSERT_UNREACHABLE("internal xpath parser error");
   return NS_ERROR_UNEXPECTED;
@@ -679,21 +693,21 @@ nsresult txExprParser::createUnionExpr(txExprLexer& lexer,
                                        Expr** aResult) {
   *aResult = nullptr;
 
-  nsAutoPtr<Expr> expr;
+  UniquePtr<Expr> expr;
   nsresult rv = createPathExpr(lexer, aContext, getter_Transfers(expr));
   NS_ENSURE_SUCCESS(rv, rv);
 
   if (lexer.peek()->mType != Token::UNION_OP) {
-    *aResult = expr.forget();
+    *aResult = expr.release();
     return NS_OK;
   }
 
-  nsAutoPtr<UnionExpr> unionExpr(new UnionExpr());
+  UniquePtr<UnionExpr> unionExpr(new UnionExpr());
 
-  rv = unionExpr->addExpr(expr);
+  rv = unionExpr->addExpr(expr.get());
   NS_ENSURE_SUCCESS(rv, rv);
 
-  expr.forget();
+  Unused << expr.release();
 
   while (lexer.peek()->mType == Token::UNION_OP) {
     lexer.nextToken();  //-- eat token
@@ -701,11 +715,11 @@ nsresult txExprParser::createUnionExpr(txExprLexer& lexer,
     rv = createPathExpr(lexer, aContext, getter_Transfers(expr));
     NS_ENSURE_SUCCESS(rv, rv);
 
-    rv = unionExpr->addExpr(expr.forget());
+    rv = unionExpr->addExpr(expr.release());
     NS_ENSURE_SUCCESS(rv, rv);
   }
 
-  *aResult = unionExpr.forget();
+  *aResult = unionExpr.release();
   return NS_OK;
 }
 
@@ -732,7 +746,7 @@ bool txExprParser::isLocationStepToken(Token* aToken) {
 nsresult txExprParser::parsePredicates(PredicateList* aPredicateList,
                                        txExprLexer& lexer,
                                        txIParseContext* aContext) {
-  nsAutoPtr<Expr> expr;
+  UniquePtr<Expr> expr;
   nsresult rv = NS_OK;
   while (lexer.peek()->mType == Token::L_BRACKET) {
     //-- eat Token
@@ -741,10 +755,10 @@ nsresult txExprParser::parsePredicates(PredicateList* aPredicateList,
     rv = createExpr(lexer, aContext, getter_Transfers(expr));
     NS_ENSURE_SUCCESS(rv, rv);
 
-    rv = aPredicateList->add(expr);
+    rv = aPredicateList->add(expr.get());
     NS_ENSURE_SUCCESS(rv, rv);
 
-    expr.forget();
+    Unused << expr.release();
 
     if (lexer.peek()->mType != Token::R_BRACKET) {
       return NS_ERROR_XPATH_BRACKET_EXPECTED;
@@ -770,14 +784,14 @@ nsresult txExprParser::parseParameters(FunctionCall* aFnCall,
     return NS_OK;
   }
 
-  nsAutoPtr<Expr> expr;
+  UniquePtr<Expr> expr;
   nsresult rv = NS_OK;
   while (1) {
     rv = createExpr(lexer, aContext, getter_Transfers(expr));
     NS_ENSURE_SUCCESS(rv, rv);
 
     if (aFnCall) {
-      rv = aFnCall->addParam(expr.forget());
+      rv = aFnCall->addParam(expr.release());
       NS_ENSURE_SUCCESS(rv, rv);
     }
 
diff --git a/dom/xslt/xpath/txExprParser.h b/dom/xslt/xpath/txExprParser.h
index b7c8b10336..36a59ceb49 100644
--- a/dom/xslt/xpath/txExprParser.h
+++ b/dom/xslt/xpath/txExprParser.h
@@ -12,7 +12,7 @@
 #define MITREXSL_EXPRPARSER_H
 
 #include "txCore.h"
-#include "nsAutoPtr.h"
+#include "mozilla/UniquePtrExtensions.h"
 #include "nsString.h"
 
 class Expr;
@@ -46,8 +46,8 @@ class txExprParser {
    * Using nsAutoPtr& to optimize passing the ownership to the
    * created binary expression objects.
    */
-  static nsresult createBinaryExpr(nsAutoPtr<Expr>& left,
-                                   nsAutoPtr<Expr>& right, Token* op,
+  static nsresult createBinaryExpr(mozilla::UniquePtr<Expr>& left,
+                                   mozilla::UniquePtr<Expr>& right, Token* op,
                                    Expr** aResult);
   static nsresult createExpr(txExprLexer& lexer, txIParseContext* aContext,
                              Expr** aResult);
diff --git a/dom/xslt/xpath/txExprResult.h b/dom/xslt/xpath/txExprResult.h
index 458eca8786..aea42046ff 100644
--- a/dom/xslt/xpath/txExprResult.h
+++ b/dom/xslt/xpath/txExprResult.h
@@ -6,7 +6,6 @@
 #define TRANSFRMX_EXPRRESULT_H
 
 #include "nsString.h"
-#include "nsAutoPtr.h"
 #include "txCore.h"
 #include "txResultRecycler.h"
 
diff --git a/dom/xslt/xpath/txFilterExpr.cpp b/dom/xslt/xpath/txFilterExpr.cpp
index f15560cc2b..926abd990e 100644
--- a/dom/xslt/xpath/txFilterExpr.cpp
+++ b/dom/xslt/xpath/txFilterExpr.cpp
@@ -6,6 +6,9 @@
 #include "txNodeSet.h"
 #include "txIXPathContext.h"
 
+using mozilla::Unused;
+using mozilla::WrapUnique;
+
 //-- Implementation of FilterExpr --/
 
 //-----------------------------/
@@ -54,15 +57,15 @@ TX_IMPL_EXPR_STUBS_BASE(FilterExpr, NODESET_RESULT)
 
 Expr* FilterExpr::getSubExprAt(uint32_t aPos) {
   if (aPos == 0) {
-    return expr;
+    return expr.get();
   }
   return PredicateList::getSubExprAt(aPos - 1);
 }
 
 void FilterExpr::setSubExprAt(uint32_t aPos, Expr* aExpr) {
   if (aPos == 0) {
-    expr.forget();
-    expr = aExpr;
+    Unused << expr.release();
+    expr = WrapUnique(aExpr);
   } else {
     PredicateList::setSubExprAt(aPos - 1, aExpr);
   }
diff --git a/dom/xslt/xpath/txForwardContext.h b/dom/xslt/xpath/txForwardContext.h
index 856b242e35..e991eb62a5 100644
--- a/dom/xslt/xpath/txForwardContext.h
+++ b/dom/xslt/xpath/txForwardContext.h
@@ -6,7 +6,6 @@
 #define __TX_XPATH_CONTEXT
 
 #include "txIXPathContext.h"
-#include "nsAutoPtr.h"
 #include "txNodeSet.h"
 
 class txForwardContext : public txIEvalContext {
diff --git a/dom/xslt/xpath/txNodeSetContext.h b/dom/xslt/xpath/txNodeSetContext.h
index 0f7d2af0e3..656e49e58f 100644
--- a/dom/xslt/xpath/txNodeSetContext.h
+++ b/dom/xslt/xpath/txNodeSetContext.h
@@ -7,7 +7,6 @@
 
 #include "txIXPathContext.h"
 #include "txNodeSet.h"
-#include "nsAutoPtr.h"
 
 class txNodeSetContext : public txIEvalContext {
  public:
diff --git a/dom/xslt/xpath/txPathExpr.cpp b/dom/xslt/xpath/txPathExpr.cpp
index 753ddcc292..27baf644da 100644
--- a/dom/xslt/xpath/txPathExpr.cpp
+++ b/dom/xslt/xpath/txPathExpr.cpp
@@ -9,6 +9,9 @@
 #include "txXMLUtils.h"
 #include "txXPathTreeWalker.h"
 
+using mozilla::Unused;
+using mozilla::WrapUnique;
+
 //------------/
 //- PathExpr -/
 //------------/
@@ -24,7 +27,7 @@ nsresult PathExpr::addExpr(Expr* aExpr, PathOperator aPathOp) {
   if (!pxi) {
     return NS_ERROR_OUT_OF_MEMORY;
   }
-  pxi->expr = aExpr;
+  pxi->expr = WrapUnique(aExpr);
   pxi->pathOp = aPathOp;
 
   return NS_OK;
@@ -77,8 +80,8 @@ nsresult PathExpr::evaluate(txIEvalContext* aContext, txAExprResult** aResult) {
         rv = aContext->recycler()->getNodeSet(getter_AddRefs(resNodes));
         NS_ENSURE_SUCCESS(rv, rv);
 
-        rv = evalDescendants(pxi.expr, eContext.getContextNode(), &eContext,
-                             resNodes);
+        rv = evalDescendants(pxi.expr.get(), eContext.getContextNode(),
+                             &eContext, resNodes);
         NS_ENSURE_SUCCESS(rv, rv);
       } else {
         RefPtr<txAExprResult> res;
@@ -178,8 +181,8 @@ Expr* PathExpr::getSubExprAt(uint32_t aPos) {
 }
 void PathExpr::setSubExprAt(uint32_t aPos, Expr* aExpr) {
   NS_ASSERTION(aPos < mItems.Length(), "setting bad subexpression index");
-  mItems[aPos].expr.forget();
-  mItems[aPos].expr = aExpr;
+  Unused << mItems[aPos].expr.release();
+  mItems[aPos].expr = WrapUnique(aExpr);
 }
 
 bool PathExpr::isSensitiveTo(ContextSensitivity aContext) {
diff --git a/dom/xslt/xpath/txResultRecycler.h b/dom/xslt/xpath/txResultRecycler.h
index 52fe79f38c..72bdc145df 100644
--- a/dom/xslt/xpath/txResultRecycler.h
+++ b/dom/xslt/xpath/txResultRecycler.h
@@ -6,7 +6,6 @@
 #define txResultRecycler_h__
 
 #include "nsCOMPtr.h"
-#include "nsAutoPtr.h"
 #include "txStack.h"
 
 class txAExprResult;
diff --git a/dom/xslt/xpath/txXPathNode.h b/dom/xslt/xpath/txXPathNode.h
index 1a1bfa90d7..3befff8afb 100644
--- a/dom/xslt/xpath/txXPathNode.h
+++ b/dom/xslt/xpath/txXPathNode.h
@@ -5,7 +5,6 @@
 #ifndef txXPathNode_h__
 #define txXPathNode_h__
 
-#include "nsAutoPtr.h"
 #include "nsIContent.h"
 #include "mozilla/dom/Document.h"
 #include "nsINode.h"
diff --git a/dom/xslt/xpath/txXPathOptimizer.cpp b/dom/xslt/xpath/txXPathOptimizer.cpp
index 34f6e762ea..11736a9be2 100644
--- a/dom/xslt/xpath/txXPathOptimizer.cpp
+++ b/dom/xslt/xpath/txXPathOptimizer.cpp
@@ -11,6 +11,9 @@
 #include "txExpr.h"
 #include "txIXPathContext.h"
 
+using mozilla::UniquePtr;
+using mozilla::Unused;
+
 class txEarlyEvalContext : public txIEvalContext {
  public:
   explicit txEarlyEvalContext(txResultRecycler* aRecycler)
@@ -218,12 +221,12 @@ nsresult txXPathOptimizer::optimizeUnion(Expr* aInExpr, Expr** aOutExpr) {
 
       // Create a txUnionNodeTest if needed
       if (!unionTest) {
-        nsAutoPtr<txNodeTest> owner(unionTest = new txUnionNodeTest);
+        UniquePtr<txNodeTest> owner(unionTest = new txUnionNodeTest);
         rv = unionTest->addNodeTest(currentStep->getNodeTest());
         NS_ENSURE_SUCCESS(rv, rv);
 
         currentStep->setNodeTest(unionTest);
-        owner.forget();
+        Unused << owner.release();
       }
 
       // Merge the nodetest into the union
diff --git a/dom/xslt/xslt/txBufferingHandler.cpp b/dom/xslt/xslt/txBufferingHandler.cpp
index db580fe492..bde8acd0df 100644
--- a/dom/xslt/xslt/txBufferingHandler.cpp
+++ b/dom/xslt/xslt/txBufferingHandler.cpp
@@ -4,6 +4,8 @@
 
 #include "txBufferingHandler.h"
 
+using mozilla::MakeUnique;
+
 class txOutputTransaction {
  public:
   enum txTransactionType {
@@ -148,7 +150,7 @@ class txAttributeAtomTransaction : public txOutputTransaction {
 
 txBufferingHandler::txBufferingHandler() : mCanAddAttribute(false) {
   MOZ_COUNT_CTOR(txBufferingHandler);
-  mBuffer = new txResultBuffer();
+  mBuffer = MakeUnique<txResultBuffer>();
 }
 
 txBufferingHandler::~txBufferingHandler() {
diff --git a/dom/xslt/xslt/txBufferingHandler.h b/dom/xslt/xslt/txBufferingHandler.h
index a40ac35815..0a5b55de05 100644
--- a/dom/xslt/xslt/txBufferingHandler.h
+++ b/dom/xslt/xslt/txBufferingHandler.h
@@ -5,10 +5,10 @@
 #ifndef txBufferingHandler_h__
 #define txBufferingHandler_h__
 
+#include "mozilla/UniquePtr.h"
 #include "txXMLEventHandler.h"
 #include "nsString.h"
 #include "nsTArray.h"
-#include "nsAutoPtr.h"
 
 class txOutputTransaction;
 
@@ -37,7 +37,7 @@ class txBufferingHandler : public txAXMLEventHandler {
   TX_DECL_TXAXMLEVENTHANDLER
 
  protected:
-  nsAutoPtr<txResultBuffer> mBuffer;
+  mozilla::UniquePtr<txResultBuffer> mBuffer;
   bool mCanAddAttribute;
 };
 
diff --git a/dom/xslt/xslt/txEXSLTFunctions.cpp b/dom/xslt/xslt/txEXSLTFunctions.cpp
index 7d2246e567..2a2fe7da52 100644
--- a/dom/xslt/xslt/txEXSLTFunctions.cpp
+++ b/dom/xslt/xslt/txEXSLTFunctions.cpp
@@ -8,6 +8,7 @@
 #include "mozilla/FloatingPoint.h"
 #include "mozilla/MacroArgs.h"
 #include "mozilla/MacroForEach.h"
+#include "mozilla/UniquePtrExtensions.h"
 
 #include "nsAtom.h"
 #include "nsGkAtoms.h"
@@ -121,7 +122,7 @@ static nsresult createAndAddToResult(nsAtom* aName, const nsAString& aValue,
   rv = aResultHolder->AppendChildTo(elem, false);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<txXPathNode> xpathNode(
+  UniquePtr<txXPathNode> xpathNode(
       txXPathNativeNode::createXPathNode(elem, true));
   NS_ENSURE_TRUE(xpathNode, NS_ERROR_OUT_OF_MEMORY);
 
@@ -257,7 +258,7 @@ nsresult txEXSLTFunctionCall::evaluate(txIEvalContext* aContext,
           nsAutoString value;
           exprResult->stringValue(value);
 
-          nsAutoPtr<txXPathNode> node;
+          UniquePtr<txXPathNode> node;
           rv = createTextNode(aContext, value, getter_Transfers(node));
           NS_ENSURE_SUCCESS(rv, rv);
 
@@ -684,10 +685,10 @@ nsresult txEXSLTRegExFunctionCall::evaluate(txIEvalContext* aContext,
       rv = aContext->recycler()->getNodeSet(getter_AddRefs(resultSet));
       NS_ENSURE_SUCCESS(rv, rv);
 
-      nsAutoPtr<txXPathNode> node;
+      UniquePtr<txXPathNode> node;
       for (nsIContent* result = docFrag->GetFirstChild(); result;
            result = result->GetNextSibling()) {
-        node = txXPathNativeNode::createXPathNode(result, true);
+        node = WrapUnique(txXPathNativeNode::createXPathNode(result, true));
         rv = resultSet->add(*node);
         NS_ENSURE_SUCCESS(rv, rv);
       }
diff --git a/dom/xslt/xslt/txExecutionState.cpp b/dom/xslt/xslt/txExecutionState.cpp
index 94afe3c230..f6d9e072df 100644
--- a/dom/xslt/xslt/txExecutionState.cpp
+++ b/dom/xslt/xslt/txExecutionState.cpp
@@ -2,6 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+#include "mozilla/UniquePtrExtensions.h"
 #include "txExecutionState.h"
 #include "txSingleNodeContext.h"
 #include "txInstructions.h"
@@ -13,10 +14,14 @@
 #include "txURIUtils.h"
 #include "txXMLParser.h"
 
+using mozilla::UniquePtr;
+using mozilla::Unused;
+using mozilla::WrapUnique;
+
 const int32_t txExecutionState::kMaxRecursionDepth = 20000;
 
 nsresult txLoadedDocumentsHash::init(const txXPathNode& aSource) {
-  mSourceDocument = txXPathNodeUtils::getOwnerDocument(aSource);
+  mSourceDocument = WrapUnique(txXPathNodeUtils::getOwnerDocument(aSource));
 
   nsAutoString baseURI;
   nsresult rv = txXPathNodeUtils::getBaseURI(*mSourceDocument, baseURI);
@@ -34,8 +39,8 @@ nsresult txLoadedDocumentsHash::init(const txXPathNode& aSource) {
   // txMozillaXSLTProcessor::TransformToFragment) it makes more sense to return
   // the real root of the source tree, which is the node where the transform
   // started.
-  PutEntry(baseURI)->mDocument =
-      txXPathNativeNode::createXPathNode(txXPathNativeNode::getNode(aSource));
+  PutEntry(baseURI)->mDocument = WrapUnique(
+      txXPathNativeNode::createXPathNode(txXPathNativeNode::getNode(aSource)));
   return NS_OK;
 }
 
@@ -46,7 +51,7 @@ txLoadedDocumentsHash::~txLoadedDocumentsHash() {
     if (NS_SUCCEEDED(rv)) {
       txLoadedDocumentEntry* entry = GetEntry(baseURI);
       if (entry) {
-        delete entry->mDocument.forget();
+        delete entry->mDocument.release();
       }
     }
   }
@@ -238,20 +243,20 @@ nsresult txExecutionState::getVariable(int32_t aNamespace, nsAtom* aLName,
       return rv;
     }
   } else {
-    nsAutoPtr<txRtfHandler> rtfHandler(new txRtfHandler);
+    UniquePtr<txRtfHandler> rtfHandler(new txRtfHandler);
 
-    rv = pushResultHandler(rtfHandler);
+    rv = pushResultHandler(rtfHandler.get());
     if (NS_FAILED(rv)) {
       popAndDeleteEvalContextUntil(mInitialEvalContext);
       return rv;
     }
 
-    rtfHandler.forget();
+    Unused << rtfHandler.release();
 
     txInstruction* prevInstr = mNextInstruction;
     // set return to nullptr to stop execution
     mNextInstruction = nullptr;
-    rv = runTemplate(var->mFirstInstruction);
+    rv = runTemplate(var->mFirstInstruction.get());
     if (NS_FAILED(rv)) {
       popAndDeleteEvalContextUntil(mInitialEvalContext);
       return rv;
@@ -267,7 +272,7 @@ nsresult txExecutionState::getVariable(int32_t aNamespace, nsAtom* aLName,
     popTemplateRule();
 
     mNextInstruction = prevInstr;
-    rtfHandler = (txRtfHandler*)popResultHandler();
+    rtfHandler = WrapUnique((txRtfHandler*)popResultHandler());
     rv = rtfHandler->getAsRTF(&aResult);
     if (NS_FAILED(rv)) {
       popAndDeleteEvalContextUntil(mInitialEvalContext);
@@ -370,7 +375,7 @@ const txXPathNode* txExecutionState::retrieveDocument(const nsAString& aUri) {
     return nullptr;
   }
 
-  MOZ_LOG(txLog::xslt, LogLevel::Debug,
+  MOZ_LOG(txLog::xslt, mozilla::LogLevel::Debug,
           ("Retrieve Document %s", NS_LossyConvertUTF16toASCII(aUri).get()));
 
   // try to get already loaded document
@@ -395,7 +400,7 @@ const txXPathNode* txExecutionState::retrieveDocument(const nsAString& aUri) {
     }
   }
 
-  return entry->mDocument;
+  return entry->mDocument.get();
 }
 
 nsresult txExecutionState::getKeyNodes(const txExpandedName& aKeyName,
@@ -415,7 +420,7 @@ txExecutionState::TemplateRule* txExecutionState::getCurrentTemplateRule() {
 txInstruction* txExecutionState::getNextInstruction() {
   txInstruction* instr = mNextInstruction;
   if (instr) {
-    mNextInstruction = instr->mNext;
+    mNextInstruction = instr->mNext.get();
   }
 
   return instr;
diff --git a/dom/xslt/xslt/txExecutionState.h b/dom/xslt/xslt/txExecutionState.h
index d03ab656ba..8ea8739e77 100644
--- a/dom/xslt/xslt/txExecutionState.h
+++ b/dom/xslt/xslt/txExecutionState.h
@@ -33,7 +33,7 @@ class txLoadedDocumentEntry : public nsStringHashKey {
   }
   ~txLoadedDocumentEntry() {
     if (mDocument) {
-      txXPathNodeUtils::release(mDocument);
+      txXPathNodeUtils::release(mDocument.get());
     }
   }
   bool LoadingFailed() {
@@ -43,7 +43,7 @@ class txLoadedDocumentEntry : public nsStringHashKey {
     return NS_FAILED(mLoadResult);
   }
 
-  nsAutoPtr<txXPathNode> mDocument;
+  mozilla::UniquePtr<txXPathNode> mDocument;
   nsresult mLoadResult;
 };
 
@@ -55,7 +55,7 @@ class txLoadedDocumentsHash : public nsTHashtable<txLoadedDocumentEntry> {
 
  private:
   friend class txExecutionState;
-  nsAutoPtr<txXPathNode> mSourceDocument;
+  mozilla::UniquePtr<txXPathNode> mSourceDocument;
 };
 
 class txExecutionState : public txIMatchContext {
@@ -124,7 +124,7 @@ class txExecutionState : public txIMatchContext {
 
   txAXMLEventHandler* mOutputHandler;
   txAXMLEventHandler* mResultHandler;
-  nsAutoPtr<txAXMLEventHandler> mObsoleteHandler;
+  mozilla::UniquePtr<txAXMLEventHandler> mObsoleteHandler;
   txAOutputHandlerFactory* mOutputHandlerFactory;
 
   RefPtr<txParameterMap> mTemplateParams;
diff --git a/dom/xslt/xslt/txFormatNumberFunctionCall.cpp b/dom/xslt/xslt/txFormatNumberFunctionCall.cpp
index b09aa4680d..67671aacc1 100644
--- a/dom/xslt/xslt/txFormatNumberFunctionCall.cpp
+++ b/dom/xslt/xslt/txFormatNumberFunctionCall.cpp
@@ -253,7 +253,7 @@ nsresult txFormatNumberFunctionCall::evaluate(txIEvalContext* aContext,
   else
     bufsize = 1 + 30;
 
-  auto buf = MakeUnique<char[]>(bufsize);
+  auto buf = mozilla::MakeUnique<char[]>(bufsize);
   int bufIntDigits, sign;
   char* endp;
   PR_dtoa(value, 0, 0, &bufIntDigits, &sign, &endp, buf.get(), bufsize - 1);
@@ -274,20 +274,23 @@ nsresult txFormatNumberFunctionCall::evaluate(txIEvalContext* aContext,
   bool carry = (0 <= i + 1) && (i + 1 < buflen) && (buf[i + 1] >= '5');
   bool hasFraction = false;
 
-  CheckedUint32 resPos = CheckedUint32(res.Length()) - 1;
+  // The number of characters in res that we haven't filled in.
+  mozilla::CheckedUint32 resRemain = mozilla::CheckedUint32(res.Length());
 
-#define CHECKED_SET_CHAR(c)                                       \
-  if (!resPos.isValid() || !res.SetCharAt(c, resPos--.value())) { \
-    ReportInvalidArg(aContext);                                   \
-    return NS_ERROR_XPATH_INVALID_ARG;                            \
+#define CHECKED_SET_CHAR(c)                                           \
+  --resRemain;                                                        \
+  if (!resRemain.isValid() || !res.SetCharAt(c, resRemain.value())) { \
+    ReportInvalidArg(aContext);                                       \
+    return NS_ERROR_XPATH_INVALID_ARG;                                \
   }
 
 #define CHECKED_TRUNCATE()             \
-  if (!resPos.isValid()) {             \
+  --resRemain;                         \
+  if (!resRemain.isValid()) {          \
     ReportInvalidArg(aContext);        \
     return NS_ERROR_XPATH_INVALID_ARG; \
   }                                    \
-  res.Truncate(resPos--.value());
+  res.Truncate(resRemain.value());
 
   // Fractions
   for (; i >= bufIntDigits; --i) {
@@ -344,9 +347,9 @@ nsresult txFormatNumberFunctionCall::evaluate(txIEvalContext* aContext,
 
   if (carry) {
     if (i % groupSize == 0) {
-      res.Insert(format->mGroupingSeparator, resPos.value() + 1);
+      res.Insert(format->mGroupingSeparator, resRemain.value());
     }
-    res.Insert((char16_t)(1 + format->mZeroDigit), resPos.value() + 1);
+    res.Insert((char16_t)(1 + format->mZeroDigit), resRemain.value());
   }
 
   if (!hasFraction && !intDigits && !carry) {
diff --git a/dom/xslt/xslt/txInstructions.cpp b/dom/xslt/xslt/txInstructions.cpp
index ab348bf72f..a59b86ff31 100644
--- a/dom/xslt/xslt/txInstructions.cpp
+++ b/dom/xslt/xslt/txInstructions.cpp
@@ -2,21 +2,25 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-#include "mozilla/Move.h"
 #include "txInstructions.h"
+
+#include <utility>
+
 #include "nsError.h"
-#include "txExpr.h"
-#include "txStylesheet.h"
-#include "txNodeSetContext.h"
-#include "txTextHandler.h"
+#include "nsGkAtoms.h"
 #include "nsIConsoleService.h"
 #include "nsServiceManagerUtils.h"
-#include "txStringUtils.h"
-#include "nsGkAtoms.h"
-#include "txRtfHandler.h"
+#include "txExecutionState.h"
+#include "txExpr.h"
+#include "txNodeSetContext.h"
 #include "txNodeSorter.h"
+#include "txRtfHandler.h"
+#include "txStringUtils.h"
+#include "txStylesheet.h"
+#include "txTextHandler.h"
 #include "txXSLTNumber.h"
-#include "txExecutionState.h"
+
+using mozilla::UniquePtr;
 
 nsresult txApplyDefaultElementTemplate::execute(txExecutionState& aEs) {
   txExecutionState::TemplateRule* rule = aEs.getCurrentTemplateRule();
@@ -86,14 +90,14 @@ nsresult txApplyTemplates::execute(txExecutionState& aEs) {
   return aEs.runTemplate(templ);
 }
 
-txAttribute::txAttribute(nsAutoPtr<Expr>&& aName, nsAutoPtr<Expr>&& aNamespace,
+txAttribute::txAttribute(UniquePtr<Expr>&& aName, UniquePtr<Expr>&& aNamespace,
                          txNamespaceMap* aMappings)
     : mName(std::move(aName)),
       mNamespace(std::move(aNamespace)),
       mMappings(aMappings) {}
 
 nsresult txAttribute::execute(txExecutionState& aEs) {
-  nsAutoPtr<txTextHandler> handler(
+  UniquePtr<txTextHandler> handler(
       static_cast<txTextHandler*>(aEs.popResultHandler()));
 
   nsAutoString name;
@@ -164,7 +168,7 @@ nsresult txCheckParam::execute(txExecutionState& aEs) {
   return NS_OK;
 }
 
-txConditionalGoto::txConditionalGoto(nsAutoPtr<Expr>&& aCondition,
+txConditionalGoto::txConditionalGoto(UniquePtr<Expr>&& aCondition,
                                      txInstruction* aTarget)
     : mCondition(std::move(aCondition)), mTarget(aTarget) {}
 
@@ -181,7 +185,7 @@ nsresult txConditionalGoto::execute(txExecutionState& aEs) {
 }
 
 nsresult txComment::execute(txExecutionState& aEs) {
-  nsAutoPtr<txTextHandler> handler(
+  UniquePtr<txTextHandler> handler(
       static_cast<txTextHandler*>(aEs.popResultHandler()));
   uint32_t length = handler->mValue.Length();
   int32_t pos = 0;
@@ -318,7 +322,7 @@ nsresult txCopy::execute(txExecutionState& aEs) {
   return NS_OK;
 }
 
-txCopyOf::txCopyOf(nsAutoPtr<Expr>&& aSelect) : mSelect(std::move(aSelect)) {}
+txCopyOf::txCopyOf(UniquePtr<Expr>&& aSelect) : mSelect(std::move(aSelect)) {}
 
 nsresult txCopyOf::execute(txExecutionState& aEs) {
   RefPtr<txAExprResult> exprRes;
@@ -410,7 +414,7 @@ nsresult txLoopNodeSet::execute(txExecutionState& aEs) {
 }
 
 txLREAttribute::txLREAttribute(int32_t aNamespaceID, nsAtom* aLocalName,
-                               nsAtom* aPrefix, nsAutoPtr<Expr>&& aValue)
+                               nsAtom* aPrefix, UniquePtr<Expr>&& aValue)
     : mNamespaceID(aNamespaceID),
       mLocalName(aLocalName),
       mPrefix(aPrefix),
@@ -440,7 +444,7 @@ nsresult txLREAttribute::execute(txExecutionState& aEs) {
 txMessage::txMessage(bool aTerminate) : mTerminate(aTerminate) {}
 
 nsresult txMessage::execute(txExecutionState& aEs) {
-  nsAutoPtr<txTextHandler> handler(
+  UniquePtr<txTextHandler> handler(
       static_cast<txTextHandler*>(aEs.popResultHandler()));
 
   nsCOMPtr<nsIConsoleService> consoleSvc =
@@ -455,10 +459,10 @@ nsresult txMessage::execute(txExecutionState& aEs) {
 }
 
 txNumber::txNumber(txXSLTNumber::LevelType aLevel,
-                   nsAutoPtr<txPattern>&& aCount, nsAutoPtr<txPattern>&& aFrom,
-                   nsAutoPtr<Expr>&& aValue, nsAutoPtr<Expr>&& aFormat,
-                   nsAutoPtr<Expr>&& aGroupingSeparator,
-                   nsAutoPtr<Expr>&& aGroupingSize)
+                   UniquePtr<txPattern>&& aCount, UniquePtr<txPattern>&& aFrom,
+                   UniquePtr<Expr>&& aValue, UniquePtr<Expr>&& aFormat,
+                   UniquePtr<Expr>&& aGroupingSeparator,
+                   UniquePtr<Expr>&& aGroupingSize)
     : mLevel(aLevel),
       mCount(std::move(aCount)),
       mFrom(std::move(aFrom)),
@@ -469,9 +473,9 @@ txNumber::txNumber(txXSLTNumber::LevelType aLevel,
 
 nsresult txNumber::execute(txExecutionState& aEs) {
   nsAutoString res;
-  nsresult rv = txXSLTNumber::createNumber(mValue, mCount, mFrom, mLevel,
-                                           mGroupingSize, mGroupingSeparator,
-                                           mFormat, aEs.getEvalContext(), res);
+  nsresult rv = txXSLTNumber::createNumber(
+      mValue.get(), mCount.get(), mFrom.get(), mLevel, mGroupingSize.get(),
+      mGroupingSeparator.get(), mFormat.get(), aEs.getEvalContext(), res);
   NS_ENSURE_SUCCESS(rv, rv);
 
   return aEs.mResultHandler->characters(res, false);
@@ -483,11 +487,11 @@ nsresult txPopParams::execute(txExecutionState& aEs) {
   return NS_OK;
 }
 
-txProcessingInstruction::txProcessingInstruction(nsAutoPtr<Expr>&& aName)
+txProcessingInstruction::txProcessingInstruction(UniquePtr<Expr>&& aName)
     : mName(std::move(aName)) {}
 
 nsresult txProcessingInstruction::execute(txExecutionState& aEs) {
-  nsAutoPtr<txTextHandler> handler(
+  UniquePtr<txTextHandler> handler(
       static_cast<txTextHandler*>(aEs.popResultHandler()));
   XMLUtils::normalizePIValue(handler->mValue);
 
@@ -506,7 +510,7 @@ nsresult txProcessingInstruction::execute(txExecutionState& aEs) {
   return aEs.mResultHandler->processingInstruction(name, handler->mValue);
 }
 
-txPushNewContext::txPushNewContext(nsAutoPtr<Expr>&& aSelect)
+txPushNewContext::txPushNewContext(UniquePtr<Expr>&& aSelect)
     : mSelect(std::move(aSelect)), mBailTarget(nullptr) {}
 
 txPushNewContext::~txPushNewContext() = default;
@@ -535,9 +539,9 @@ nsresult txPushNewContext::execute(txExecutionState& aEs) {
   uint32_t i, count = mSortKeys.Length();
   for (i = 0; i < count; ++i) {
     SortKey& sort = mSortKeys[i];
-    rv = sorter.addSortElement(sort.mSelectExpr, sort.mLangExpr,
-                               sort.mDataTypeExpr, sort.mOrderExpr,
-                               sort.mCaseOrderExpr, aEs.getEvalContext());
+    rv = sorter.addSortElement(sort.mSelectExpr.get(), sort.mLangExpr.get(),
+                               sort.mDataTypeExpr.get(), sort.mOrderExpr.get(),
+                               sort.mCaseOrderExpr.get(), aEs.getEvalContext());
     NS_ENSURE_SUCCESS(rv, rv);
   }
   RefPtr<txNodeSet> sortedNodes;
@@ -558,11 +562,11 @@ nsresult txPushNewContext::execute(txExecutionState& aEs) {
   return NS_OK;
 }
 
-nsresult txPushNewContext::addSort(nsAutoPtr<Expr>&& aSelectExpr,
-                                   nsAutoPtr<Expr>&& aLangExpr,
-                                   nsAutoPtr<Expr>&& aDataTypeExpr,
-                                   nsAutoPtr<Expr>&& aOrderExpr,
-                                   nsAutoPtr<Expr>&& aCaseOrderExpr) {
+nsresult txPushNewContext::addSort(UniquePtr<Expr>&& aSelectExpr,
+                                   UniquePtr<Expr>&& aLangExpr,
+                                   UniquePtr<Expr>&& aDataTypeExpr,
+                                   UniquePtr<Expr>&& aOrderExpr,
+                                   UniquePtr<Expr>&& aCaseOrderExpr) {
   if (SortKey* key = mSortKeys.AppendElement()) {
     // workaround for not triggering the Copy Constructor
     key->mSelectExpr = std::move(aSelectExpr);
@@ -626,7 +630,7 @@ nsresult txReturn::execute(txExecutionState& aEs) {
   return NS_OK;
 }
 
-txSetParam::txSetParam(const txExpandedName& aName, nsAutoPtr<Expr>&& aValue)
+txSetParam::txSetParam(const txExpandedName& aName, UniquePtr<Expr>&& aValue)
     : mName(aName), mValue(std::move(aValue)) {}
 
 nsresult txSetParam::execute(txExecutionState& aEs) {
@@ -640,7 +644,7 @@ nsresult txSetParam::execute(txExecutionState& aEs) {
     rv = mValue->evaluate(aEs.getEvalContext(), getter_AddRefs(exprRes));
     NS_ENSURE_SUCCESS(rv, rv);
   } else {
-    nsAutoPtr<txRtfHandler> rtfHandler(
+    UniquePtr<txRtfHandler> rtfHandler(
         static_cast<txRtfHandler*>(aEs.popResultHandler()));
     rv = rtfHandler->getAsRTF(getter_AddRefs(exprRes));
     NS_ENSURE_SUCCESS(rv, rv);
@@ -653,7 +657,7 @@ nsresult txSetParam::execute(txExecutionState& aEs) {
 }
 
 txSetVariable::txSetVariable(const txExpandedName& aName,
-                             nsAutoPtr<Expr>&& aValue)
+                             UniquePtr<Expr>&& aValue)
     : mName(aName), mValue(std::move(aValue)) {}
 
 nsresult txSetVariable::execute(txExecutionState& aEs) {
@@ -663,7 +667,7 @@ nsresult txSetVariable::execute(txExecutionState& aEs) {
     rv = mValue->evaluate(aEs.getEvalContext(), getter_AddRefs(exprRes));
     NS_ENSURE_SUCCESS(rv, rv);
   } else {
-    nsAutoPtr<txRtfHandler> rtfHandler(
+    UniquePtr<txRtfHandler> rtfHandler(
         static_cast<txRtfHandler*>(aEs.popResultHandler()));
     rv = rtfHandler->getAsRTF(getter_AddRefs(exprRes));
     NS_ENSURE_SUCCESS(rv, rv);
@@ -672,8 +676,8 @@ nsresult txSetVariable::execute(txExecutionState& aEs) {
   return aEs.bindVariable(mName, exprRes);
 }
 
-txStartElement::txStartElement(nsAutoPtr<Expr>&& aName,
-                               nsAutoPtr<Expr>&& aNamespace,
+txStartElement::txStartElement(UniquePtr<Expr>&& aName,
+                               UniquePtr<Expr>&& aNamespace,
                                txNamespaceMap* aMappings)
     : mName(std::move(aName)),
       mNamespace(std::move(aNamespace)),
@@ -758,7 +762,7 @@ nsresult txText::execute(txExecutionState& aEs) {
   return aEs.mResultHandler->characters(mStr, mDOE);
 }
 
-txValueOf::txValueOf(nsAutoPtr<Expr>&& aExpr, bool aDOE)
+txValueOf::txValueOf(UniquePtr<Expr>&& aExpr, bool aDOE)
     : mExpr(std::move(aExpr)), mDOE(aDOE) {}
 
 nsresult txValueOf::execute(txExecutionState& aEs) {
diff --git a/dom/xslt/xslt/txInstructions.h b/dom/xslt/xslt/txInstructions.h
index 63edb2152a..427f20a309 100644
--- a/dom/xslt/xslt/txInstructions.h
+++ b/dom/xslt/xslt/txInstructions.h
@@ -5,13 +5,13 @@
 #ifndef TRANSFRMX_TXINSTRUCTIONS_H
 #define TRANSFRMX_TXINSTRUCTIONS_H
 
+#include "mozilla/UniquePtr.h"
 #include "nsCOMPtr.h"
 #include "txCore.h"
 #include "nsString.h"
 #include "txXMLUtils.h"
 #include "txExpandedName.h"
 #include "txNamespaceMap.h"
-#include "nsAutoPtr.h"
 #include "txXSLTNumber.h"
 #include "nsTArray.h"
 
@@ -26,7 +26,7 @@ class txInstruction : public txObject {
 
   virtual nsresult execute(txExecutionState& aEs) = 0;
 
-  nsAutoPtr<txInstruction> mNext;
+  mozilla::UniquePtr<txInstruction> mNext;
 };
 
 #define TX_DECL_TXINSTRUCTION \
@@ -58,13 +58,13 @@ class txApplyTemplates : public txInstruction {
 
 class txAttribute : public txInstruction {
  public:
-  txAttribute(nsAutoPtr<Expr>&& aName, nsAutoPtr<Expr>&& aNamespace,
-              txNamespaceMap* aMappings);
+  txAttribute(mozilla::UniquePtr<Expr>&& aName,
+              mozilla::UniquePtr<Expr>&& aNamespace, txNamespaceMap* aMappings);
 
   TX_DECL_TXINSTRUCTION
 
-  nsAutoPtr<Expr> mName;
-  nsAutoPtr<Expr> mNamespace;
+  mozilla::UniquePtr<Expr> mName;
+  mozilla::UniquePtr<Expr> mNamespace;
   RefPtr<txNamespaceMap> mMappings;
 };
 
@@ -89,11 +89,12 @@ class txCheckParam : public txInstruction {
 
 class txConditionalGoto : public txInstruction {
  public:
-  txConditionalGoto(nsAutoPtr<Expr>&& aCondition, txInstruction* aTarget);
+  txConditionalGoto(mozilla::UniquePtr<Expr>&& aCondition,
+                    txInstruction* aTarget);
 
   TX_DECL_TXINSTRUCTION
 
-  nsAutoPtr<Expr> mCondition;
+  mozilla::UniquePtr<Expr> mCondition;
   txInstruction* mTarget;
 };
 
@@ -118,11 +119,11 @@ class txCopy : public txCopyBase {
 
 class txCopyOf : public txCopyBase {
  public:
-  explicit txCopyOf(nsAutoPtr<Expr>&& aSelect);
+  explicit txCopyOf(mozilla::UniquePtr<Expr>&& aSelect);
 
   TX_DECL_TXINSTRUCTION
 
-  nsAutoPtr<Expr> mSelect;
+  mozilla::UniquePtr<Expr> mSelect;
 };
 
 class txEndElement : public txInstruction {
@@ -165,7 +166,7 @@ class txLoopNodeSet : public txInstruction {
 class txLREAttribute : public txInstruction {
  public:
   txLREAttribute(int32_t aNamespaceID, nsAtom* aLocalName, nsAtom* aPrefix,
-                 nsAutoPtr<Expr>&& aValue);
+                 mozilla::UniquePtr<Expr>&& aValue);
 
   TX_DECL_TXINSTRUCTION
 
@@ -173,7 +174,7 @@ class txLREAttribute : public txInstruction {
   RefPtr<nsAtom> mLocalName;
   RefPtr<nsAtom> mLowercaseLocalName;
   RefPtr<nsAtom> mPrefix;
-  nsAutoPtr<Expr> mValue;
+  mozilla::UniquePtr<Expr> mValue;
 };
 
 class txMessage : public txInstruction {
@@ -187,20 +188,23 @@ class txMessage : public txInstruction {
 
 class txNumber : public txInstruction {
  public:
-  txNumber(txXSLTNumber::LevelType aLevel, nsAutoPtr<txPattern>&& aCount,
-           nsAutoPtr<txPattern>&& aFrom, nsAutoPtr<Expr>&& aValue,
-           nsAutoPtr<Expr>&& aFormat, nsAutoPtr<Expr>&& aGroupingSeparator,
-           nsAutoPtr<Expr>&& aGroupingSize);
+  txNumber(txXSLTNumber::LevelType aLevel,
+           mozilla::UniquePtr<txPattern>&& aCount,
+           mozilla::UniquePtr<txPattern>&& aFrom,
+           mozilla::UniquePtr<Expr>&& aValue,
+           mozilla::UniquePtr<Expr>&& aFormat,
+           mozilla::UniquePtr<Expr>&& aGroupingSeparator,
+           mozilla::UniquePtr<Expr>&& aGroupingSize);
 
   TX_DECL_TXINSTRUCTION
 
   txXSLTNumber::LevelType mLevel;
-  nsAutoPtr<txPattern> mCount;
-  nsAutoPtr<txPattern> mFrom;
-  nsAutoPtr<Expr> mValue;
-  nsAutoPtr<Expr> mFormat;
-  nsAutoPtr<Expr> mGroupingSeparator;
-  nsAutoPtr<Expr> mGroupingSize;
+  mozilla::UniquePtr<txPattern> mCount;
+  mozilla::UniquePtr<txPattern> mFrom;
+  mozilla::UniquePtr<Expr> mValue;
+  mozilla::UniquePtr<Expr> mFormat;
+  mozilla::UniquePtr<Expr> mGroupingSeparator;
+  mozilla::UniquePtr<Expr> mGroupingSize;
 };
 
 class txPopParams : public txInstruction {
@@ -210,35 +214,36 @@ class txPopParams : public txInstruction {
 
 class txProcessingInstruction : public txInstruction {
  public:
-  explicit txProcessingInstruction(nsAutoPtr<Expr>&& aName);
+  explicit txProcessingInstruction(mozilla::UniquePtr<Expr>&& aName);
 
   TX_DECL_TXINSTRUCTION
 
-  nsAutoPtr<Expr> mName;
+  mozilla::UniquePtr<Expr> mName;
 };
 
 class txPushNewContext : public txInstruction {
  public:
-  explicit txPushNewContext(nsAutoPtr<Expr>&& aSelect);
+  explicit txPushNewContext(mozilla::UniquePtr<Expr>&& aSelect);
   ~txPushNewContext();
 
   TX_DECL_TXINSTRUCTION
 
-  nsresult addSort(nsAutoPtr<Expr>&& aSelectExpr, nsAutoPtr<Expr>&& aLangExpr,
-                   nsAutoPtr<Expr>&& aDataTypeExpr,
-                   nsAutoPtr<Expr>&& aOrderExpr,
-                   nsAutoPtr<Expr>&& aCaseOrderExpr);
+  nsresult addSort(mozilla::UniquePtr<Expr>&& aSelectExpr,
+                   mozilla::UniquePtr<Expr>&& aLangExpr,
+                   mozilla::UniquePtr<Expr>&& aDataTypeExpr,
+                   mozilla::UniquePtr<Expr>&& aOrderExpr,
+                   mozilla::UniquePtr<Expr>&& aCaseOrderExpr);
 
   struct SortKey {
-    nsAutoPtr<Expr> mSelectExpr;
-    nsAutoPtr<Expr> mLangExpr;
-    nsAutoPtr<Expr> mDataTypeExpr;
-    nsAutoPtr<Expr> mOrderExpr;
-    nsAutoPtr<Expr> mCaseOrderExpr;
+    mozilla::UniquePtr<Expr> mSelectExpr;
+    mozilla::UniquePtr<Expr> mLangExpr;
+    mozilla::UniquePtr<Expr> mDataTypeExpr;
+    mozilla::UniquePtr<Expr> mOrderExpr;
+    mozilla::UniquePtr<Expr> mCaseOrderExpr;
   };
 
   nsTArray<SortKey> mSortKeys;
-  nsAutoPtr<Expr> mSelect;
+  mozilla::UniquePtr<Expr> mSelect;
   txInstruction* mBailTarget;
 };
 
@@ -282,33 +287,34 @@ class txReturn : public txInstruction {
 
 class txSetParam : public txInstruction {
  public:
-  txSetParam(const txExpandedName& aName, nsAutoPtr<Expr>&& aValue);
+  txSetParam(const txExpandedName& aName, mozilla::UniquePtr<Expr>&& aValue);
 
   TX_DECL_TXINSTRUCTION
 
   txExpandedName mName;
-  nsAutoPtr<Expr> mValue;
+  mozilla::UniquePtr<Expr> mValue;
 };
 
 class txSetVariable : public txInstruction {
  public:
-  txSetVariable(const txExpandedName& aName, nsAutoPtr<Expr>&& aValue);
+  txSetVariable(const txExpandedName& aName, mozilla::UniquePtr<Expr>&& aValue);
 
   TX_DECL_TXINSTRUCTION
 
   txExpandedName mName;
-  nsAutoPtr<Expr> mValue;
+  mozilla::UniquePtr<Expr> mValue;
 };
 
 class txStartElement : public txInstruction {
  public:
-  txStartElement(nsAutoPtr<Expr>&& aName, nsAutoPtr<Expr>&& aNamespace,
+  txStartElement(mozilla::UniquePtr<Expr>&& aName,
+                 mozilla::UniquePtr<Expr>&& aNamespace,
                  txNamespaceMap* aMappings);
 
   TX_DECL_TXINSTRUCTION
 
-  nsAutoPtr<Expr> mName;
-  nsAutoPtr<Expr> mNamespace;
+  mozilla::UniquePtr<Expr> mName;
+  mozilla::UniquePtr<Expr> mNamespace;
   RefPtr<txNamespaceMap> mMappings;
 };
 
@@ -336,11 +342,11 @@ class txText : public txInstruction {
 
 class txValueOf : public txInstruction {
  public:
-  txValueOf(nsAutoPtr<Expr>&& aExpr, bool aDOE);
+  txValueOf(mozilla::UniquePtr<Expr>&& aExpr, bool aDOE);
 
   TX_DECL_TXINSTRUCTION
 
-  nsAutoPtr<Expr> mExpr;
+  mozilla::UniquePtr<Expr> mExpr;
   bool mDOE;
 };
 
diff --git a/dom/xslt/xslt/txKey.h b/dom/xslt/xslt/txKey.h
index 21ea2bf728..1d1746f172 100644
--- a/dom/xslt/xslt/txKey.h
+++ b/dom/xslt/xslt/txKey.h
@@ -101,7 +101,8 @@ class txXSLKey {
    * @param aUse    use-expression
    * @return false if an error occurred, true otherwise
    */
-  bool addKey(nsAutoPtr<txPattern>&& aMatch, nsAutoPtr<Expr>&& aUse);
+  bool addKey(mozilla::UniquePtr<txPattern>&& aMatch,
+              mozilla::UniquePtr<Expr>&& aUse);
 
   /**
    * Indexes a subtree and adds it to the hash of key values
@@ -140,8 +141,8 @@ class txXSLKey {
    * represents one match/use pair
    */
   struct Key {
-    nsAutoPtr<txPattern> matchPattern;
-    nsAutoPtr<Expr> useExpr;
+    mozilla::UniquePtr<txPattern> matchPattern;
+    mozilla::UniquePtr<Expr> useExpr;
   };
 
   /**
diff --git a/dom/xslt/xslt/txKeyFunctionCall.cpp b/dom/xslt/xslt/txKeyFunctionCall.cpp
index a238e0e0b0..879b89b8e8 100644
--- a/dom/xslt/xslt/txKeyFunctionCall.cpp
+++ b/dom/xslt/xslt/txKeyFunctionCall.cpp
@@ -2,16 +2,17 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-#include "txExecutionState.h"
+#include <utility>
+
+#include "mozilla/HashFunctions.h"
 #include "nsGkAtoms.h"
-#include "txSingleNodeContext.h"
-#include "txXSLTFunctions.h"
 #include "nsReadableUtils.h"
+#include "txExecutionState.h"
 #include "txKey.h"
-#include "txXSLTPatterns.h"
 #include "txNamespaceMap.h"
-#include "mozilla/HashFunctions.h"
-#include "mozilla/Move.h"
+#include "txSingleNodeContext.h"
+#include "txXSLTFunctions.h"
+#include "txXSLTPatterns.h"
 
 using namespace mozilla;
 
@@ -218,7 +219,7 @@ nsresult txKeyHash::init() {
  * @param aUse    use-expression
  * @return false if an error occurred, true otherwise
  */
-bool txXSLKey::addKey(nsAutoPtr<txPattern>&& aMatch, nsAutoPtr<Expr>&& aUse) {
+bool txXSLKey::addKey(UniquePtr<txPattern>&& aMatch, UniquePtr<Expr>&& aUse) {
   if (!aMatch || !aUse) return false;
 
   Key* key = mKeys.AppendElement();
diff --git a/dom/xslt/xslt/txMozillaStylesheetCompiler.cpp b/dom/xslt/xslt/txMozillaStylesheetCompiler.cpp
index 109bb644c7..bbeb8a7fab 100644
--- a/dom/xslt/xslt/txMozillaStylesheetCompiler.cpp
+++ b/dom/xslt/xslt/txMozillaStylesheetCompiler.cpp
@@ -37,6 +37,7 @@
 #include "ReferrerInfo.h"
 
 using namespace mozilla;
+using mozilla::dom::Document;
 using mozilla::dom::ReferrerPolicy;
 
 static NS_DEFINE_CID(kCParserCID, NS_PARSER_CID);
@@ -407,12 +408,10 @@ nsresult txCompileObserver::startLoad(nsIURI* aUri,
 
   nsCOMPtr<nsIHttpChannel> httpChannel(do_QueryInterface(channel));
   if (httpChannel) {
-    nsCOMPtr<nsIURI> referrerURI;
-    aReferrerPrincipal->GetURI(getter_AddRefs(referrerURI));
-    if (referrerURI) {
-      DebugOnly<nsresult> rv;
-      nsCOMPtr<nsIReferrerInfo> referrerInfo =
-          new dom::ReferrerInfo(referrerURI, aReferrerPolicy);
+    nsCOMPtr<nsIReferrerInfo> referrerInfo;
+    nsresult rv = aReferrerPrincipal->CreateReferrerInfo(
+        aReferrerPolicy, getter_AddRefs(referrerInfo));
+    if (NS_SUCCEEDED(rv)) {
       rv = httpChannel->SetReferrerInfoWithoutClone(referrerInfo);
       MOZ_ASSERT(NS_SUCCEEDED(rv));
     }
@@ -554,7 +553,7 @@ nsresult txSyncCompileObserver::loadURI(const nsAString& aUri,
   if (mProcessor) {
     source = mProcessor->GetSourceContentModel();
   }
-  nsAutoSyncOperation sync(source ? source->OwnerDoc() : nullptr);
+  dom::nsAutoSyncOperation sync(source ? source->OwnerDoc() : nullptr);
   nsCOMPtr<Document> document;
 
   rv = nsSyncLoadService::LoadDocument(
diff --git a/dom/xslt/xslt/txMozillaXMLOutput.cpp b/dom/xslt/xslt/txMozillaXMLOutput.cpp
index b179445372..2b410d1831 100644
--- a/dom/xslt/xslt/txMozillaXMLOutput.cpp
+++ b/dom/xslt/xslt/txMozillaXMLOutput.cpp
@@ -18,7 +18,6 @@
 #include "nsNameSpaceManager.h"
 #include "txStringUtils.h"
 #include "txURIUtils.h"
-#include "nsIStyleSheetLinkingElement.h"
 #include "nsIDocumentTransformer.h"
 #include "mozilla/StyleSheetInlines.h"
 #include "mozilla/css/Loader.h"
@@ -288,11 +287,9 @@ nsresult txMozillaXMLOutput::endElement() {
 
   if (mCreatingNewDocument) {
     // Handle all sorts of stylesheets
-    nsCOMPtr<nsIStyleSheetLinkingElement> ssle =
-        do_QueryInterface(mCurrentNode);
-    if (ssle) {
-      ssle->SetEnableUpdates(true);
-      auto updateOrError = ssle->UpdateStyleSheet(mNotifier);
+    if (auto* linkStyle = LinkStyle::FromNode(*mCurrentNode)) {
+      linkStyle->SetEnableUpdates(true);
+      auto updateOrError = linkStyle->UpdateStyleSheet(mNotifier);
       if (mNotifier && updateOrError.isOk() &&
           updateOrError.unwrap().ShouldBlock()) {
         mNotifier->AddPendingStylesheet();
@@ -351,21 +348,20 @@ nsresult txMozillaXMLOutput::processingInstruction(const nsString& aTarget,
   nsCOMPtr<nsIContent> pi =
       NS_NewXMLProcessingInstruction(mNodeInfoManager, aTarget, aData);
 
-  nsCOMPtr<nsIStyleSheetLinkingElement> ssle;
+  LinkStyle* linkStyle = nullptr;
   if (mCreatingNewDocument) {
-    ssle = do_QueryInterface(pi);
-    if (ssle) {
-      ssle->InitStyleLinkElement(false);
-      ssle->SetEnableUpdates(false);
+    linkStyle = LinkStyle::FromNode(*pi);
+    if (linkStyle) {
+      linkStyle->SetEnableUpdates(false);
     }
   }
 
   rv = mCurrentNode->AppendChildTo(pi, true);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  if (ssle) {
-    ssle->SetEnableUpdates(true);
-    auto updateOrError = ssle->UpdateStyleSheet(mNotifier);
+  if (linkStyle) {
+    linkStyle->SetEnableUpdates(true);
+    auto updateOrError = linkStyle->UpdateStyleSheet(mNotifier);
     if (mNotifier && updateOrError.isOk() &&
         updateOrError.unwrap().ShouldBlock()) {
       mNotifier->AddPendingStylesheet();
@@ -497,11 +493,8 @@ nsresult txMozillaXMLOutput::startElementInternal(nsAtom* aPrefix,
 
   if (mCreatingNewDocument) {
     // Handle all sorts of stylesheets
-    nsCOMPtr<nsIStyleSheetLinkingElement> ssle =
-        do_QueryInterface(mOpenedElement);
-    if (ssle) {
-      ssle->InitStyleLinkElement(false);
-      ssle->SetEnableUpdates(false);
+    if (auto* linkStyle = LinkStyle::FromNodeOrNull(mOpenedElement)) {
+      linkStyle->SetEnableUpdates(false);
     }
   }
 
diff --git a/dom/xslt/xslt/txMozillaXMLOutput.h b/dom/xslt/xslt/txMozillaXMLOutput.h
index ac21b32651..724cdb0be6 100644
--- a/dom/xslt/xslt/txMozillaXMLOutput.h
+++ b/dom/xslt/xslt/txMozillaXMLOutput.h
@@ -6,7 +6,6 @@
 #define TRANSFRMX_MOZILLA_XML_OUTPUT_H
 
 #include "txXMLEventHandler.h"
-#include "nsAutoPtr.h"
 #include "nsIScriptLoaderObserver.h"
 #include "txOutputFormat.h"
 #include "nsCOMArray.h"
diff --git a/dom/xslt/xslt/txMozillaXSLTProcessor.cpp b/dom/xslt/xslt/txMozillaXSLTProcessor.cpp
index 0c6fabd22d..f5334a5a34 100644
--- a/dom/xslt/xslt/txMozillaXSLTProcessor.cpp
+++ b/dom/xslt/xslt/txMozillaXSLTProcessor.cpp
@@ -76,26 +76,26 @@ nsresult txToDocHandlerFactory::createHandlerWith(
     }
 
     case eHTMLOutput: {
-      nsAutoPtr<txMozillaXMLOutput> handler(
+      UniquePtr<txMozillaXMLOutput> handler(
           new txMozillaXMLOutput(aFormat, mObserver));
 
       nsresult rv = handler->createResultDocument(
           EmptyString(), kNameSpaceID_None, mSourceDocument, mDocumentIsData);
       if (NS_SUCCEEDED(rv)) {
-        *aHandler = handler.forget();
+        *aHandler = handler.release();
       }
 
       return rv;
     }
 
     case eTextOutput: {
-      nsAutoPtr<txMozillaTextOutput> handler(
+      UniquePtr<txMozillaTextOutput> handler(
           new txMozillaTextOutput(mObserver));
 
       nsresult rv =
           handler->createResultDocument(mSourceDocument, mDocumentIsData);
       if (NS_SUCCEEDED(rv)) {
-        *aHandler = handler.forget();
+        *aHandler = handler.release();
       }
 
       return rv;
@@ -119,26 +119,26 @@ nsresult txToDocHandlerFactory::createHandlerWith(
 
     case eXMLOutput:
     case eHTMLOutput: {
-      nsAutoPtr<txMozillaXMLOutput> handler(
+      UniquePtr<txMozillaXMLOutput> handler(
           new txMozillaXMLOutput(aFormat, mObserver));
 
       nsresult rv = handler->createResultDocument(aName, aNsID, mSourceDocument,
                                                   mDocumentIsData);
       if (NS_SUCCEEDED(rv)) {
-        *aHandler = handler.forget();
+        *aHandler = handler.release();
       }
 
       return rv;
     }
 
     case eTextOutput: {
-      nsAutoPtr<txMozillaTextOutput> handler(
+      UniquePtr<txMozillaTextOutput> handler(
           new txMozillaTextOutput(mObserver));
 
       nsresult rv =
           handler->createResultDocument(mSourceDocument, mDocumentIsData);
       if (NS_SUCCEEDED(rv)) {
-        *aHandler = handler.forget();
+        *aHandler = handler.release();
       }
 
       return rv;
@@ -393,7 +393,7 @@ txMozillaXSLTProcessor::AddXSLTParam(const nsString& aName,
   RefPtr<txAExprResult> value;
   if (!aSelect.IsVoid()) {
     // Set up context
-    nsAutoPtr<txXPathNode> contextNode(
+    UniquePtr<txXPathNode> contextNode(
         txXPathNativeNode::createXPathNode(aContext));
     NS_ENSURE_TRUE(contextNode, NS_ERROR_OUT_OF_MEMORY);
 
@@ -405,7 +405,7 @@ txMozillaXSLTProcessor::AddXSLTParam(const nsString& aName,
                                     mRecycler);
 
     // Parse
-    nsAutoPtr<Expr> expr;
+    UniquePtr<Expr> expr;
     rv = txExprParser::createExpr(aSelect, &paramContext,
                                   getter_Transfers(expr));
     NS_ENSURE_SUCCESS(rv, rv);
@@ -539,7 +539,7 @@ already_AddRefed<Document> txMozillaXSLTProcessor::TransformToDocument(
 
 nsresult txMozillaXSLTProcessor::TransformToDoc(Document** aResult,
                                                 bool aCreateDataDocument) {
-  nsAutoPtr<txXPathNode> sourceNode(
+  UniquePtr<txXPathNode> sourceNode(
       txXPathNativeNode::createXPathNode(mSource));
   if (!sourceNode) {
     return NS_ERROR_OUT_OF_MEMORY;
@@ -606,7 +606,7 @@ already_AddRefed<DocumentFragment> txMozillaXSLTProcessor::TransformToFragment(
     return nullptr;
   }
 
-  nsAutoPtr<txXPathNode> sourceNode(
+  UniquePtr<txXPathNode> sourceNode(
       txXPathNativeNode::createXPathNode(&aSource));
   if (!sourceNode) {
     aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
@@ -1207,7 +1207,7 @@ nsresult txVariable::Convert(nsIVariant* aValue, txAExprResult** aResult) {
 
       nsCOMPtr<nsINode> node = do_QueryInterface(supports);
       if (node) {
-        nsAutoPtr<txXPathNode> xpathNode(
+        UniquePtr<txXPathNode> xpathNode(
             txXPathNativeNode::createXPathNode(node));
         if (!xpathNode) {
           return NS_ERROR_FAILURE;
@@ -1239,7 +1239,7 @@ nsresult txVariable::Convert(nsIVariant* aValue, txAExprResult** aResult) {
 
         uint32_t i;
         for (i = 0; i < length; ++i) {
-          nsAutoPtr<txXPathNode> xpathNode(
+          UniquePtr<txXPathNode> xpathNode(
               txXPathNativeNode::createXPathNode(nodeList->Item(i)));
           if (!xpathNode) {
             return NS_ERROR_FAILURE;
@@ -1300,7 +1300,7 @@ nsresult txVariable::Convert(nsIVariant* aValue, txAExprResult** aResult) {
         nsCOMPtr<nsINode> node = do_QueryInterface(supports);
         NS_ASSERTION(node, "Huh, we checked this in SetParameter?");
 
-        nsAutoPtr<txXPathNode> xpathNode(
+        UniquePtr<txXPathNode> xpathNode(
             txXPathNativeNode::createXPathNode(node));
         if (!xpathNode) {
           while (i < count) {
diff --git a/dom/xslt/xslt/txMozillaXSLTProcessor.h b/dom/xslt/xslt/txMozillaXSLTProcessor.h
index 4d374a2aa5..77e26aea8c 100644
--- a/dom/xslt/xslt/txMozillaXSLTProcessor.h
+++ b/dom/xslt/xslt/txMozillaXSLTProcessor.h
@@ -5,7 +5,6 @@
 #ifndef TRANSFRMX_TXMOZILLAXSLTPROCESSOR_H
 #define TRANSFRMX_TXMOZILLAXSLTPROCESSOR_H
 
-#include "nsAutoPtr.h"
 #include "nsStubMutationObserver.h"
 #include "nsIDocumentTransformer.h"
 #include "txExpandedNameMap.h"
@@ -15,10 +14,12 @@
 #include "mozilla/Attributes.h"
 #include "mozilla/ErrorResult.h"
 #include "mozilla/dom/BindingDeclarations.h"
+#include "mozilla/dom/ReferrerPolicyBinding.h"
 #include "mozilla/dom/XSLTProcessorBinding.h"
 
 class nsINode;
 class nsIURI;
+class nsIVariant;
 class txStylesheet;
 class txResultRecycler;
 class txIGlobalParameter;
diff --git a/dom/xslt/xslt/txNodeSorter.cpp b/dom/xslt/xslt/txNodeSorter.cpp
index 52bb0a2025..454e6903e0 100644
--- a/dom/xslt/xslt/txNodeSorter.cpp
+++ b/dom/xslt/xslt/txNodeSorter.cpp
@@ -16,6 +16,7 @@
 
 using mozilla::CheckedUint32;
 using mozilla::MakeUniqueFallible;
+using mozilla::UniquePtr;
 
 /*
  * Sorts Nodes as specified by the W3C XSLT 1.0 Recommendation
@@ -36,7 +37,7 @@ nsresult txNodeSorter::addSortElement(Expr* aSelectExpr, Expr* aLangExpr,
                                       Expr* aDataTypeExpr, Expr* aOrderExpr,
                                       Expr* aCaseOrderExpr,
                                       txIEvalContext* aContext) {
-  nsAutoPtr<SortKey> key(new SortKey);
+  UniquePtr<SortKey> key(new SortKey);
   nsresult rv = NS_OK;
 
   // Select
@@ -101,10 +102,7 @@ nsresult txNodeSorter::addSortElement(Expr* aSelectExpr, Expr* aLangExpr,
   }
 
   // mSortKeys owns key now.
-  rv = mSortKeys.add(key);
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  key.forget();
+  mSortKeys.add(key.release());
   mNKeys++;
 
   return NS_OK;
diff --git a/dom/xslt/xslt/txPatternParser.cpp b/dom/xslt/xslt/txPatternParser.cpp
index 6157ed1e82..cd9f70ed37 100644
--- a/dom/xslt/xslt/txPatternParser.cpp
+++ b/dom/xslt/xslt/txPatternParser.cpp
@@ -11,6 +11,8 @@
 #include "txStylesheetCompiler.h"
 #include "txPatternOptimizer.h"
 
+using mozilla::UniquePtr;
+
 nsresult txPatternParser::createPattern(const nsString& aPattern,
                                         txIParseContext* aContext,
                                         txPattern** aResult) {
@@ -20,7 +22,7 @@ nsresult txPatternParser::createPattern(const nsString& aPattern,
     // XXX error report parsing error
     return rv;
   }
-  nsAutoPtr<txPattern> pattern;
+  UniquePtr<txPattern> pattern;
   rv = createUnionPattern(lexer, aContext, *getter_Transfers(pattern));
   if (NS_FAILED(rv)) {
     // XXX error report parsing error
@@ -29,10 +31,10 @@ nsresult txPatternParser::createPattern(const nsString& aPattern,
 
   txPatternOptimizer optimizer;
   txPattern* newPattern = nullptr;
-  rv = optimizer.optimize(pattern, &newPattern);
+  rv = optimizer.optimize(pattern.get(), &newPattern);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  *aResult = newPattern ? newPattern : pattern.forget();
+  *aResult = newPattern ? newPattern : pattern.release();
 
   return NS_OK;
 }
@@ -276,11 +278,11 @@ nsresult txPatternParser::createStepPattern(txExprLexer& aLexer,
     NS_ENSURE_SUCCESS(rv, rv);
   }
 
-  nsAutoPtr<txStepPattern> step(new txStepPattern(nodeTest, isAttr));
-  rv = parsePredicates(step, aLexer, aContext);
+  UniquePtr<txStepPattern> step(new txStepPattern(nodeTest, isAttr));
+  rv = parsePredicates(step.get(), aLexer, aContext);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  aPattern = step.forget();
+  aPattern = step.release();
 
   return NS_OK;
 }
diff --git a/dom/xslt/xslt/txRtfHandler.cpp b/dom/xslt/xslt/txRtfHandler.cpp
index 4736e1c5d5..ee952659ee 100644
--- a/dom/xslt/xslt/txRtfHandler.cpp
+++ b/dom/xslt/xslt/txRtfHandler.cpp
@@ -3,9 +3,11 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "txRtfHandler.h"
-#include "mozilla/Move.h"
 
-txResultTreeFragment::txResultTreeFragment(nsAutoPtr<txResultBuffer>&& aBuffer)
+#include <utility>
+
+txResultTreeFragment::txResultTreeFragment(
+    mozilla::UniquePtr<txResultBuffer>&& aBuffer)
     : txAExprResult(nullptr), mBuffer(std::move(aBuffer)) {}
 
 short txResultTreeFragment::getResultType() { return RESULT_TREE_FRAGMENT; }
diff --git a/dom/xslt/xslt/txRtfHandler.h b/dom/xslt/xslt/txRtfHandler.h
index df2934747f..473232494b 100644
--- a/dom/xslt/xslt/txRtfHandler.h
+++ b/dom/xslt/xslt/txRtfHandler.h
@@ -12,7 +12,7 @@
 
 class txResultTreeFragment : public txAExprResult {
  public:
-  explicit txResultTreeFragment(nsAutoPtr<txResultBuffer>&& aBuffer);
+  explicit txResultTreeFragment(mozilla::UniquePtr<txResultBuffer>&& aBuffer);
 
   TX_DECL_EXPRRESULT
 
@@ -21,13 +21,13 @@ class txResultTreeFragment : public txAExprResult {
   void setNode(const txXPathNode* aNode) {
     NS_ASSERTION(!mNode, "Already converted!");
 
-    mNode = aNode;
+    mNode = mozilla::WrapUnique(aNode);
   }
-  const txXPathNode* getNode() const { return mNode; }
+  const txXPathNode* getNode() const { return mNode.get(); }
 
  private:
-  nsAutoPtr<txResultBuffer> mBuffer;
-  nsAutoPtr<const txXPathNode> mNode;
+  mozilla::UniquePtr<txResultBuffer> mBuffer;
+  mozilla::UniquePtr<const txXPathNode> mNode;
 };
 
 class txRtfHandler : public txBufferingHandler {
diff --git a/dom/xslt/xslt/txStylesheet.cpp b/dom/xslt/xslt/txStylesheet.cpp
index ddbef5e831..b3c3764105 100644
--- a/dom/xslt/xslt/txStylesheet.cpp
+++ b/dom/xslt/xslt/txStylesheet.cpp
@@ -2,20 +2,25 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-#include "mozilla/FloatingPoint.h"
-#include "mozilla/Move.h"
-
 #include "txStylesheet.h"
+
+#include <utility>
+
+#include "mozilla/FloatingPoint.h"
 #include "txExpr.h"
-#include "txXSLTPatterns.h"
-#include "txToplevelItems.h"
 #include "txInstructions.h"
-#include "txXSLTFunctions.h"
-#include "txLog.h"
 #include "txKey.h"
+#include "txLog.h"
+#include "txToplevelItems.h"
 #include "txXPathTreeWalker.h"
+#include "txXSLTFunctions.h"
+#include "txXSLTPatterns.h"
 
 using mozilla::LogLevel;
+using mozilla::MakeUnique;
+using mozilla::UniquePtr;
+using mozilla::Unused;
+using mozilla::WrapUnique;
 
 txStylesheet::txStylesheet() : mRootFrame(nullptr) {}
 
@@ -24,37 +29,39 @@ nsresult txStylesheet::init() {
 
   // Create default templates
   // element/root template
-  mContainerTemplate = new txPushParams;
+  mContainerTemplate = MakeUnique<txPushParams>();
 
-  nsAutoPtr<txNodeTest> nt(new txNodeTypeTest(txNodeTypeTest::NODE_TYPE));
-  nsAutoPtr<Expr> nodeExpr(new LocationStep(nt, LocationStep::CHILD_AXIS));
-  nt.forget();
+  UniquePtr<txNodeTest> nt(new txNodeTypeTest(txNodeTypeTest::NODE_TYPE));
+  UniquePtr<Expr> nodeExpr(
+      new LocationStep(nt.get(), LocationStep::CHILD_AXIS));
+  Unused << nt.release();
 
   txPushNewContext* pushContext = new txPushNewContext(std::move(nodeExpr));
-  mContainerTemplate->mNext = pushContext;
+  mContainerTemplate->mNext = WrapUnique(pushContext);
 
   txApplyDefaultElementTemplate* applyTemplates =
       new txApplyDefaultElementTemplate;
-  pushContext->mNext = applyTemplates;
+  pushContext->mNext = WrapUnique(applyTemplates);
 
   txLoopNodeSet* loopNodeSet = new txLoopNodeSet(applyTemplates);
-  applyTemplates->mNext = loopNodeSet;
+  applyTemplates->mNext = WrapUnique(loopNodeSet);
 
   txPopParams* popParams = new txPopParams;
-  pushContext->mBailTarget = loopNodeSet->mNext = popParams;
+  loopNodeSet->mNext = WrapUnique(popParams);
+  pushContext->mBailTarget = loopNodeSet->mNext.get();
 
-  popParams->mNext = new txReturn();
+  popParams->mNext = MakeUnique<txReturn>();
 
   // attribute/textnode template
-  nt = new txNodeTypeTest(txNodeTypeTest::NODE_TYPE);
-  nodeExpr = new LocationStep(nt, LocationStep::SELF_AXIS);
-  nt.forget();
+  nt = MakeUnique<txNodeTypeTest>(txNodeTypeTest::NODE_TYPE);
+  nodeExpr = MakeUnique<LocationStep>(nt.get(), LocationStep::SELF_AXIS);
+  Unused << nt.release();
 
-  mCharactersTemplate = new txValueOf(std::move(nodeExpr), false);
-  mCharactersTemplate->mNext = new txReturn();
+  mCharactersTemplate = MakeUnique<txValueOf>(std::move(nodeExpr), false);
+  mCharactersTemplate->mNext = MakeUnique<txReturn>();
 
   // pi/comment/namespace template
-  mEmptyTemplate = new txReturn();
+  mEmptyTemplate = MakeUnique<txReturn>();
 
   return NS_OK;
 }
@@ -125,7 +132,7 @@ nsresult txStylesheet::findTemplate(const txXPathNode& aNode,
           *aTemplate = templ.mFirstInstruction;
           *aImportFrame = frame;
 #if defined(TX_TO_STRING)
-          match = templ.mMatch;
+          match = templ.mMatch.get();
 #endif
         }
       }
@@ -161,12 +168,12 @@ nsresult txStylesheet::findTemplate(const txXPathNode& aNode,
     // and a root (if it is orphaned)
     if (txXPathNodeUtils::isAttribute(aNode) ||
         txXPathNodeUtils::isText(aNode)) {
-      *aTemplate = mCharactersTemplate;
+      *aTemplate = mCharactersTemplate.get();
     } else if (txXPathNodeUtils::isElement(aNode) ||
                txXPathNodeUtils::isRoot(aNode)) {
-      *aTemplate = mContainerTemplate;
+      *aTemplate = mContainerTemplate.get();
     } else {
-      *aTemplate = mEmptyTemplate;
+      *aTemplate = mEmptyTemplate.get();
     }
   }
 
@@ -226,7 +233,7 @@ nsresult txStylesheet::isStripSpaceAllowed(const txXPathNode& aNode,
   // check Whitespace stipping handling list against given Node
   int32_t i;
   for (i = 0; i < frameCount; ++i) {
-    txStripSpaceTest* sst = mStripSpaceTests[i];
+    const auto& sst = mStripSpaceTests[i];
     bool matched;
     nsresult rv = sst->matches(node, aContext, matched);
     NS_ENSURE_SUCCESS(rv, rv);
@@ -247,8 +254,7 @@ nsresult txStylesheet::doneCompiling() {
   nsresult rv = NS_OK;
   // Collect all importframes into a single ordered list
   txListIterator frameIter(&mImportFrames);
-  rv = frameIter.addAfter(mRootFrame);
-  NS_ENSURE_SUCCESS(rv, rv);
+  frameIter.addAfter(mRootFrame);
 
   mRootFrame = nullptr;
   frameIter.next();
@@ -311,11 +317,11 @@ nsresult txStylesheet::doneCompiling() {
   }
 
   if (!mDecimalFormats.get(txExpandedName())) {
-    nsAutoPtr<txDecimalFormat> format(new txDecimalFormat);
-    rv = mDecimalFormats.add(txExpandedName(), format);
+    UniquePtr<txDecimalFormat> format(new txDecimalFormat);
+    rv = mDecimalFormats.add(txExpandedName(), format.get());
     NS_ENSURE_SUCCESS(rv, rv);
 
-    format.forget();
+    Unused << format.release();
   }
 
   return NS_OK;
@@ -325,15 +331,14 @@ nsresult txStylesheet::addTemplate(txTemplateItem* aTemplate,
                                    ImportFrame* aImportFrame) {
   NS_ASSERTION(aTemplate, "missing template");
 
-  txInstruction* instr = aTemplate->mFirstInstruction;
-  nsresult rv = mTemplateInstructions.add(instr);
-  NS_ENSURE_SUCCESS(rv, rv);
+  txInstruction* instr = aTemplate->mFirstInstruction.get();
+  mTemplateInstructions.add(instr);
 
   // mTemplateInstructions now owns the instructions
-  aTemplate->mFirstInstruction.forget();
+  Unused << aTemplate->mFirstInstruction.release();
 
   if (!aTemplate->mName.isNull()) {
-    rv = mNamedTemplates.add(aTemplate->mName, instr);
+    nsresult rv = mNamedTemplates.add(aTemplate->mName, instr);
     NS_ENSURE_TRUE(NS_SUCCEEDED(rv) || rv == NS_ERROR_XSLT_ALREADY_SET, rv);
   }
 
@@ -348,21 +353,22 @@ nsresult txStylesheet::addTemplate(txTemplateItem* aTemplate,
       aImportFrame->mMatchableTemplates.get(aTemplate->mMode);
 
   if (!templates) {
-    nsAutoPtr<nsTArray<MatchableTemplate> > newList(
+    UniquePtr<nsTArray<MatchableTemplate> > newList(
         new nsTArray<MatchableTemplate>);
-    rv = aImportFrame->mMatchableTemplates.set(aTemplate->mMode, newList);
+    nsresult rv =
+        aImportFrame->mMatchableTemplates.set(aTemplate->mMode, newList.get());
     NS_ENSURE_SUCCESS(rv, rv);
 
-    templates = newList.forget();
+    templates = newList.release();
   }
 
   // Add the simple patterns to the list of matchable templates, according
   // to default priority
-  nsAutoPtr<txPattern> simple = std::move(aTemplate->mMatch);
-  nsAutoPtr<txPattern> unionPattern;
+  UniquePtr<txPattern> simple = std::move(aTemplate->mMatch);
+  UniquePtr<txPattern> unionPattern;
   if (simple->getType() == txPattern::UNION_PATTERN) {
     unionPattern = std::move(simple);
-    simple = unionPattern->getSubPatternAt(0);
+    simple = WrapUnique(unionPattern->getSubPatternAt(0));
     unionPattern->setSubPatternAt(0, nullptr);
   }
 
@@ -390,7 +396,7 @@ nsresult txStylesheet::addTemplate(txTemplateItem* aTemplate,
     nt->mPriority = priority;
 
     if (unionPattern) {
-      simple = unionPattern->getSubPatternAt(unionPos);
+      simple = WrapUnique(unionPattern->getSubPatternAt(unionPos));
       if (simple) {
         unionPattern->setSubPatternAt(unionPos, nullptr);
       }
@@ -411,10 +417,7 @@ nsresult txStylesheet::addFrames(txListIterator& aInsertIter) {
       txImportItem* import = static_cast<txImportItem*>(item);
       import->mFrame->mFirstNotImported =
           static_cast<ImportFrame*>(aInsertIter.next());
-      rv = aInsertIter.addBefore(import->mFrame);
-      NS_ENSURE_SUCCESS(rv, rv);
-
-      import->mFrame.forget();
+      aInsertIter.addBefore(import->mFrame.release());
       aInsertIter.previous();
       rv = addFrames(aInsertIter);
       NS_ENSURE_SUCCESS(rv, rv);
@@ -453,20 +456,20 @@ nsresult txStylesheet::addAttributeSet(txAttributeSetItem* aAttributeSetItem) {
   txInstruction* oldInstr = mAttributeSets.get(aAttributeSetItem->mName);
   if (!oldInstr) {
     rv = mAttributeSets.add(aAttributeSetItem->mName,
-                            aAttributeSetItem->mFirstInstruction);
+                            aAttributeSetItem->mFirstInstruction.get());
     NS_ENSURE_SUCCESS(rv, rv);
 
-    aAttributeSetItem->mFirstInstruction.forget();
+    Unused << aAttributeSetItem->mFirstInstruction.release();
 
     return NS_OK;
   }
 
   // We need to prepend the new instructions before the existing ones.
-  txInstruction* instr = aAttributeSetItem->mFirstInstruction;
+  txInstruction* instr = aAttributeSetItem->mFirstInstruction.get();
   txInstruction* lastNonReturn = nullptr;
   while (instr->mNext) {
     lastNonReturn = instr;
-    instr = instr->mNext;
+    instr = instr->mNext.get();
   }
 
   if (!lastNonReturn) {
@@ -475,12 +478,13 @@ nsresult txStylesheet::addAttributeSet(txAttributeSetItem* aAttributeSetItem) {
   }
 
   rv = mAttributeSets.set(aAttributeSetItem->mName,
-                          aAttributeSetItem->mFirstInstruction);
+                          aAttributeSetItem->mFirstInstruction.get());
   NS_ENSURE_SUCCESS(rv, rv);
 
-  aAttributeSetItem->mFirstInstruction.forget();
+  Unused << aAttributeSetItem->mFirstInstruction.release();
 
-  lastNonReturn->mNext = oldInstr;  // ...and link up the old instructions.
+  lastNonReturn->mNext =
+      WrapUnique(oldInstr);  // ...and link up the old instructions.
 
   return NS_OK;
 }
@@ -489,20 +493,20 @@ nsresult txStylesheet::addGlobalVariable(txVariableItem* aVariable) {
   if (mGlobalVariables.get(aVariable->mName)) {
     return NS_OK;
   }
-  nsAutoPtr<GlobalVariable> var(new GlobalVariable(
+  UniquePtr<GlobalVariable> var(new GlobalVariable(
       std::move(aVariable->mValue), std::move(aVariable->mFirstInstruction),
       aVariable->mIsParam));
-  nsresult rv = mGlobalVariables.add(aVariable->mName, var);
+  nsresult rv = mGlobalVariables.add(aVariable->mName, var.get());
   NS_ENSURE_SUCCESS(rv, rv);
 
-  var.forget();
+  Unused << var.release();
 
   return NS_OK;
 }
 
 nsresult txStylesheet::addKey(const txExpandedName& aName,
-                              nsAutoPtr<txPattern> aMatch,
-                              nsAutoPtr<Expr> aUse) {
+                              UniquePtr<txPattern> aMatch,
+                              UniquePtr<Expr> aUse) {
   nsresult rv = NS_OK;
 
   txXSLKey* xslKey = mKeys.get(aName);
@@ -521,18 +525,19 @@ nsresult txStylesheet::addKey(const txExpandedName& aName,
 }
 
 nsresult txStylesheet::addDecimalFormat(const txExpandedName& aName,
-                                        nsAutoPtr<txDecimalFormat>&& aFormat) {
+                                        UniquePtr<txDecimalFormat>&& aFormat) {
   txDecimalFormat* existing = mDecimalFormats.get(aName);
   if (existing) {
-    NS_ENSURE_TRUE(existing->isEqual(aFormat), NS_ERROR_XSLT_PARSE_FAILURE);
+    NS_ENSURE_TRUE(existing->isEqual(aFormat.get()),
+                   NS_ERROR_XSLT_PARSE_FAILURE);
 
     return NS_OK;
   }
 
-  nsresult rv = mDecimalFormats.add(aName, aFormat);
+  nsresult rv = mDecimalFormats.add(aName, aFormat.get());
   NS_ENSURE_SUCCESS(rv, rv);
 
-  aFormat.forget();
+  Unused << aFormat.release();
 
   return NS_OK;
 }
@@ -544,8 +549,8 @@ txStylesheet::ImportFrame::~ImportFrame() {
   }
 }
 
-txStylesheet::GlobalVariable::GlobalVariable(nsAutoPtr<Expr>&& aExpr,
-                                             nsAutoPtr<txInstruction>&& aInstr,
+txStylesheet::GlobalVariable::GlobalVariable(UniquePtr<Expr>&& aExpr,
+                                             UniquePtr<txInstruction>&& aInstr,
                                              bool aIsParam)
     : mExpr(std::move(aExpr)),
       mFirstInstruction(std::move(aInstr)),
diff --git a/dom/xslt/xslt/txStylesheet.h b/dom/xslt/xslt/txStylesheet.h
index 02cfcdae87..1503fd813c 100644
--- a/dom/xslt/xslt/txStylesheet.h
+++ b/dom/xslt/xslt/txStylesheet.h
@@ -53,18 +53,19 @@ class txStylesheet final {
   /**
    * Add a key to the stylesheet
    */
-  nsresult addKey(const txExpandedName& aName, nsAutoPtr<txPattern> aMatch,
-                  nsAutoPtr<Expr> aUse);
+  nsresult addKey(const txExpandedName& aName,
+                  mozilla::UniquePtr<txPattern> aMatch,
+                  mozilla::UniquePtr<Expr> aUse);
 
   /**
    * Add a decimal-format to the stylesheet
    */
   nsresult addDecimalFormat(const txExpandedName& aName,
-                            nsAutoPtr<txDecimalFormat>&& aFormat);
+                            mozilla::UniquePtr<txDecimalFormat>&& aFormat);
 
   struct MatchableTemplate {
     txInstruction* mFirstInstruction;
-    nsAutoPtr<txPattern> mMatch;
+    mozilla::UniquePtr<txPattern> mMatch;
     double mPriority;
   };
 
@@ -88,11 +89,12 @@ class txStylesheet final {
 
   class GlobalVariable : public txObject {
    public:
-    GlobalVariable(nsAutoPtr<Expr>&& aExpr,
-                   nsAutoPtr<txInstruction>&& aFirstInstruction, bool aIsParam);
+    GlobalVariable(mozilla::UniquePtr<Expr>&& aExpr,
+                   mozilla::UniquePtr<txInstruction>&& aFirstInstruction,
+                   bool aIsParam);
 
-    nsAutoPtr<Expr> mExpr;
-    nsAutoPtr<txInstruction> mFirstInstruction;
+    mozilla::UniquePtr<Expr> mExpr;
+    mozilla::UniquePtr<txInstruction> mFirstInstruction;
     bool mIsParam;
   };
 
@@ -136,12 +138,12 @@ class txStylesheet final {
   txOwningExpandedNameMap<txXSLKey> mKeys;
 
   // Array of all txStripSpaceTests, sorted in acending order
-  nsTArray<nsAutoPtr<txStripSpaceTest> > mStripSpaceTests;
+  nsTArray<mozilla::UniquePtr<txStripSpaceTest> > mStripSpaceTests;
 
   // Default templates
-  nsAutoPtr<txInstruction> mContainerTemplate;
-  nsAutoPtr<txInstruction> mCharactersTemplate;
-  nsAutoPtr<txInstruction> mEmptyTemplate;
+  mozilla::UniquePtr<txInstruction> mContainerTemplate;
+  mozilla::UniquePtr<txInstruction> mCharactersTemplate;
+  mozilla::UniquePtr<txInstruction> mEmptyTemplate;
 };
 
 /**
diff --git a/dom/xslt/xslt/txStylesheetCompileHandlers.cpp b/dom/xslt/xslt/txStylesheetCompileHandlers.cpp
index 4988ad595f..4be6dab215 100644
--- a/dom/xslt/xslt/txStylesheetCompileHandlers.cpp
+++ b/dom/xslt/xslt/txStylesheetCompileHandlers.cpp
@@ -2,21 +2,22 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+#include "txStylesheetCompileHandlers.h"
+
+#include <utility>
+
 #include "mozilla/ArrayUtils.h"
 #include "mozilla/FloatingPoint.h"
-#include "mozilla/Move.h"
-
-#include "txStylesheetCompiler.h"
-#include "txStylesheetCompileHandlers.h"
-#include "nsWhitespaceTokenizer.h"
-#include "txInstructions.h"
 #include "nsGkAtoms.h"
+#include "nsWhitespaceTokenizer.h"
 #include "txCore.h"
+#include "txInstructions.h"
+#include "txNamespaceMap.h"
+#include "txPatternParser.h"
 #include "txStringUtils.h"
 #include "txStylesheet.h"
+#include "txStylesheetCompiler.h"
 #include "txToplevelItems.h"
-#include "txPatternParser.h"
-#include "txNamespaceMap.h"
 #include "txURIUtils.h"
 #include "txXSLTFunctions.h"
 
@@ -93,9 +94,8 @@ static nsresult parseUseAttrSets(txStylesheetAttr* aAttributes,
     rv = name.init(tok.nextToken(), aState.mElementContext->mMappings, false);
     NS_ENSURE_SUCCESS(rv, rv);
 
-    nsAutoPtr<txInstruction> instr(new txInsertAttrSet(name));
-    rv = aState.addInstruction(std::move(instr));
-    NS_ENSURE_SUCCESS(rv, rv);
+    UniquePtr<txInstruction> instr(new txInsertAttrSet(name));
+    aState.addInstruction(std::move(instr));
   }
   return NS_OK;
 }
@@ -139,7 +139,7 @@ static nsresult getQNameAttr(txStylesheetAttr* aAttributes, int32_t aAttrCount,
 static nsresult getExprAttr(txStylesheetAttr* aAttributes, int32_t aAttrCount,
                             nsAtom* aName, bool aRequired,
                             txStylesheetCompilerState& aState,
-                            nsAutoPtr<Expr>& aExpr) {
+                            UniquePtr<Expr>& aExpr) {
   aExpr = nullptr;
   txStylesheetAttr* attr = nullptr;
   nsresult rv = getStyleAttr(aAttributes, aAttrCount, kNameSpaceID_None, aName,
@@ -152,7 +152,7 @@ static nsresult getExprAttr(txStylesheetAttr* aAttributes, int32_t aAttrCount,
   if (NS_FAILED(rv) && aState.ignoreError(rv)) {
     // use default value in fcp for not required exprs
     if (aRequired) {
-      aExpr = new txErrorExpr(
+      aExpr = MakeUnique<txErrorExpr>(
 #ifdef TX_TO_STRING
           attr->mValue
 #endif
@@ -169,7 +169,7 @@ static nsresult getExprAttr(txStylesheetAttr* aAttributes, int32_t aAttrCount,
 static nsresult getAVTAttr(txStylesheetAttr* aAttributes, int32_t aAttrCount,
                            nsAtom* aName, bool aRequired,
                            txStylesheetCompilerState& aState,
-                           nsAutoPtr<Expr>& aAVT) {
+                           UniquePtr<Expr>& aAVT) {
   aAVT = nullptr;
   txStylesheetAttr* attr = nullptr;
   nsresult rv = getStyleAttr(aAttributes, aAttrCount, kNameSpaceID_None, aName,
@@ -182,7 +182,7 @@ static nsresult getAVTAttr(txStylesheetAttr* aAttributes, int32_t aAttrCount,
   if (NS_FAILED(rv) && aState.fcp()) {
     // use default value in fcp for not required exprs
     if (aRequired) {
-      aAVT = new txErrorExpr(
+      aAVT = MakeUnique<txErrorExpr>(
 #ifdef TX_TO_STRING
           attr->mValue
 #endif
@@ -200,7 +200,7 @@ static nsresult getPatternAttr(txStylesheetAttr* aAttributes,
                                int32_t aAttrCount, nsAtom* aName,
                                bool aRequired,
                                txStylesheetCompilerState& aState,
-                               nsAutoPtr<txPattern>& aPattern) {
+                               UniquePtr<txPattern>& aPattern) {
   aPattern = nullptr;
   txStylesheetAttr* attr = nullptr;
   nsresult rv = getStyleAttr(aAttributes, aAttrCount, kNameSpaceID_None, aName,
@@ -424,14 +424,13 @@ static nsresult txFnStartLREStylesheet(int32_t aNamespaceID, nsAtom* aLocalName,
   txExpandedName nullExpr;
   double prio = UnspecifiedNaN<double>();
 
-  nsAutoPtr<txPattern> match(new txRootPattern());
-  nsAutoPtr<txTemplateItem> templ(
+  UniquePtr<txPattern> match(new txRootPattern());
+  UniquePtr<txTemplateItem> templ(
       new txTemplateItem(std::move(match), nullExpr, nullExpr, prio));
-  aState.openInstructionContainer(templ);
-  rv = aState.addToplevelItem(templ);
-  NS_ENSURE_SUCCESS(rv, rv);
+  aState.openInstructionContainer(templ.get());
+  aState.addToplevelItem(templ.get());
 
-  templ.forget();
+  Unused << templ.release();
 
   rv = aState.pushHandlerTable(gTxTemplateHandler);
   NS_ENSURE_SUCCESS(rv, rv);
@@ -446,9 +445,8 @@ static nsresult txFnEndLREStylesheet(txStylesheetCompilerState& aState) {
 
   aState.popHandlerTable();
 
-  nsAutoPtr<txInstruction> instr(new txReturn());
-  rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  UniquePtr<txInstruction> instr(new txReturn());
+  aState.addInstruction(std::move(instr));
 
   aState.closeInstructionContainer();
 
@@ -513,13 +511,12 @@ static nsresult txFnStartAttributeSet(int32_t aNamespaceID, nsAtom* aLocalName,
                     name);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<txAttributeSetItem> attrSet(new txAttributeSetItem(name));
-  aState.openInstructionContainer(attrSet);
+  UniquePtr<txAttributeSetItem> attrSet(new txAttributeSetItem(name));
+  aState.openInstructionContainer(attrSet.get());
 
-  rv = aState.addToplevelItem(attrSet);
-  NS_ENSURE_SUCCESS(rv, rv);
+  aState.addToplevelItem(attrSet.get());
 
-  attrSet.forget();
+  Unused << attrSet.release();
 
   rv = parseUseAttrSets(aAttributes, aAttrCount, false, aState);
   NS_ENSURE_SUCCESS(rv, rv);
@@ -530,9 +527,8 @@ static nsresult txFnStartAttributeSet(int32_t aNamespaceID, nsAtom* aLocalName,
 static nsresult txFnEndAttributeSet(txStylesheetCompilerState& aState) {
   aState.popHandlerTable();
 
-  nsAutoPtr<txInstruction> instr(new txReturn());
-  nsresult rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  UniquePtr<txInstruction> instr(new txReturn());
+  aState.addInstruction(std::move(instr));
 
   aState.closeInstructionContainer();
 
@@ -551,7 +547,7 @@ static nsresult txFnStartDecimalFormat(int32_t aNamespaceID, nsAtom* aLocalName,
                     name);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<txDecimalFormat> format(new txDecimalFormat);
+  UniquePtr<txDecimalFormat> format(new txDecimalFormat);
   rv = getCharAttr(aAttributes, aAttrCount, nsGkAtoms::decimalSeparator, false,
                    aState, format->mDecimalSeparator);
   NS_ENSURE_SUCCESS(rv, rv);
@@ -618,21 +614,20 @@ static nsresult txFnStartImport(int32_t aNamespaceID, nsAtom* aLocalName,
                                 nsAtom* aPrefix, txStylesheetAttr* aAttributes,
                                 int32_t aAttrCount,
                                 txStylesheetCompilerState& aState) {
-  nsAutoPtr<txImportItem> import(new txImportItem);
-  import->mFrame = new txStylesheet::ImportFrame;
-  nsresult rv = aState.addToplevelItem(import);
-  NS_ENSURE_SUCCESS(rv, rv);
+  UniquePtr<txImportItem> import(new txImportItem);
+  import->mFrame = MakeUnique<txStylesheet::ImportFrame>();
+  aState.addToplevelItem(import.get());
 
-  txImportItem* importPtr = import.forget();
+  txImportItem* importPtr = import.release();
 
   txStylesheetAttr* attr = nullptr;
-  rv = getStyleAttr(aAttributes, aAttrCount, kNameSpaceID_None, nsGkAtoms::href,
-                    true, &attr);
+  nsresult rv = getStyleAttr(aAttributes, aAttrCount, kNameSpaceID_None,
+                             nsGkAtoms::href, true, &attr);
   NS_ENSURE_SUCCESS(rv, rv);
 
   nsAutoString absUri;
   URIUtils::resolveHref(attr->mValue, aState.mElementContext->mBaseURI, absUri);
-  rv = aState.loadImportedStylesheet(absUri, importPtr->mFrame);
+  rv = aState.loadImportedStylesheet(absUri, importPtr->mFrame.get());
   NS_ENSURE_SUCCESS(rv, rv);
 
   return aState.pushHandlerTable(gTxIgnoreHandler);
@@ -681,12 +676,12 @@ static nsresult txFnStartKey(int32_t aNamespaceID, nsAtom* aLocalName,
 
   aState.mDisAllowed = txIParseContext::KEY_FUNCTION;
 
-  nsAutoPtr<txPattern> match;
+  UniquePtr<txPattern> match;
   rv = getPatternAttr(aAttributes, aAttrCount, nsGkAtoms::match, true, aState,
                       match);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<Expr> use;
+  UniquePtr<Expr> use;
   rv = getExprAttr(aAttributes, aAttrCount, nsGkAtoms::use, true, aState, use);
   NS_ENSURE_SUCCESS(rv, rv);
 
@@ -737,7 +732,7 @@ static nsresult txFnStartOutput(int32_t aNamespaceID, nsAtom* aLocalName,
                                 txStylesheetCompilerState& aState) {
   nsresult rv = NS_OK;
 
-  nsAutoPtr<txOutputItem> item(new txOutputItem);
+  UniquePtr<txOutputItem> item(new txOutputItem);
 
   txExpandedName methodExpName;
   rv = getQNameAttr(aAttributes, aAttrCount, nsGkAtoms::method, false, aState,
@@ -797,14 +792,12 @@ static nsresult txFnStartOutput(int32_t aNamespaceID, nsAtom* aLocalName,
   if (attr) {
     nsWhitespaceTokenizer tokens(attr->mValue);
     while (tokens.hasMoreTokens()) {
-      nsAutoPtr<txExpandedName> qname(new txExpandedName());
+      UniquePtr<txExpandedName> qname(new txExpandedName());
       rv = qname->init(tokens.nextToken(), aState.mElementContext->mMappings,
                        false);
       NS_ENSURE_SUCCESS(rv, rv);
 
-      rv = item->mFormat.mCDATASectionElements.add(qname);
-      NS_ENSURE_SUCCESS(rv, rv);
-      qname.forget();
+      item->mFormat.mCDATASectionElements.add(qname.release());
     }
   }
 
@@ -818,10 +811,7 @@ static nsresult txFnStartOutput(int32_t aNamespaceID, nsAtom* aLocalName,
     item->mFormat.mMediaType = attr->mValue;
   }
 
-  rv = aState.addToplevelItem(item);
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  item.forget();
+  aState.addToplevelItem(item.release());
 
   return aState.pushHandlerTable(gTxIgnoreHandler);
 }
@@ -845,7 +835,7 @@ static nsresult txFnStartStripSpace(int32_t aNamespaceID, nsAtom* aLocalName,
 
   bool strip = aLocalName == nsGkAtoms::stripSpace;
 
-  nsAutoPtr<txStripSpaceItem> stripItem(new txStripSpaceItem);
+  UniquePtr<txStripSpaceItem> stripItem(new txStripSpaceItem);
   nsWhitespaceTokenizer tokenizer(attr->mValue);
   while (tokenizer.hasMoreTokens()) {
     const nsAString& name = tokenizer.nextToken();
@@ -884,18 +874,15 @@ static nsresult txFnStartStripSpace(int32_t aNamespaceID, nsAtom* aLocalName,
       ns = aState.mElementContext->mMappings->lookupNamespace(prefix);
       NS_ENSURE_TRUE(ns != kNameSpaceID_Unknown, NS_ERROR_FAILURE);
     }
-    nsAutoPtr<txStripSpaceTest> sst(
+    UniquePtr<txStripSpaceTest> sst(
         new txStripSpaceTest(prefix, localName, ns, strip));
-    rv = stripItem->addStripSpaceTest(sst);
+    rv = stripItem->addStripSpaceTest(sst.get());
     NS_ENSURE_SUCCESS(rv, rv);
 
-    sst.forget();
+    Unused << sst.release();
   }
 
-  rv = aState.addToplevelItem(stripItem);
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  stripItem.forget();
+  aState.addToplevelItem(stripItem.release());
 
   return aState.pushHandlerTable(gTxIgnoreHandler);
 }
@@ -928,18 +915,15 @@ static nsresult txFnStartTemplate(int32_t aNamespaceID, nsAtom* aLocalName,
                      aState, prio);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<txPattern> match;
+  UniquePtr<txPattern> match;
   rv = getPatternAttr(aAttributes, aAttrCount, nsGkAtoms::match, name.isNull(),
                       aState, match);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<txTemplateItem> templ(
+  UniquePtr<txTemplateItem> templ(
       new txTemplateItem(std::move(match), name, mode, prio));
-  aState.openInstructionContainer(templ);
-  rv = aState.addToplevelItem(templ);
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  templ.forget();
+  aState.openInstructionContainer(templ.get());
+  aState.addToplevelItem(templ.release());
 
   return aState.pushHandlerTable(gTxParamHandler);
 }
@@ -947,9 +931,8 @@ static nsresult txFnStartTemplate(int32_t aNamespaceID, nsAtom* aLocalName,
 static nsresult txFnEndTemplate(txStylesheetCompilerState& aState) {
   aState.popHandlerTable();
 
-  nsAutoPtr<txInstruction> instr(new txReturn());
-  nsresult rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  UniquePtr<txInstruction> instr(new txReturn());
+  aState.addInstruction(std::move(instr));
 
   aState.closeInstructionContainer();
 
@@ -968,15 +951,15 @@ static nsresult txFnStartTopVariable(int32_t aNamespaceID, nsAtom* aLocalName,
                     name);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<Expr> select;
+  UniquePtr<Expr> select;
   rv = getExprAttr(aAttributes, aAttrCount, nsGkAtoms::select, false, aState,
                    select);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<txVariableItem> var(new txVariableItem(
+  UniquePtr<txVariableItem> var(new txVariableItem(
       name, std::move(select), aLocalName == nsGkAtoms::param));
-  aState.openInstructionContainer(var);
-  rv = aState.pushPtr(var, aState.eVariableItem);
+  aState.openInstructionContainer(var.get());
+  rv = aState.pushPtr(var.get(), aState.eVariableItem);
   NS_ENSURE_SUCCESS(rv, rv);
 
   if (var->mValue) {
@@ -988,10 +971,7 @@ static nsresult txFnStartTopVariable(int32_t aNamespaceID, nsAtom* aLocalName,
     NS_ENSURE_SUCCESS(rv, rv);
   }
 
-  rv = aState.addToplevelItem(var);
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  var.forget();
+  aState.addToplevelItem(var.release());
 
   return NS_OK;
 }
@@ -1005,12 +985,11 @@ static nsresult txFnEndTopVariable(txStylesheetCompilerState& aState) {
   if (prev == gTxTopVariableHandler) {
     // No children were found.
     NS_ASSERTION(!var->mValue, "There shouldn't be a select-expression here");
-    var->mValue = new txLiteralExpr(EmptyString());
+    var->mValue = MakeUnique<txLiteralExpr>(EmptyString());
   } else if (!var->mValue) {
     // If we don't have a select-expression there mush be children.
-    nsAutoPtr<txInstruction> instr(new txReturn());
-    nsresult rv = aState.addInstruction(std::move(instr));
-    NS_ENSURE_SUCCESS(rv, rv);
+    UniquePtr<txInstruction> instr(new txReturn());
+    aState.addInstruction(std::move(instr));
   }
 
   aState.closeInstructionContainer();
@@ -1056,10 +1035,9 @@ static nsresult txFnStartLRE(int32_t aNamespaceID, nsAtom* aLocalName,
                              txStylesheetCompilerState& aState) {
   nsresult rv = NS_OK;
 
-  nsAutoPtr<txInstruction> instr(
+  UniquePtr<txInstruction> instr(
       new txStartLREElement(aNamespaceID, aLocalName, aPrefix));
-  rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  aState.addInstruction(std::move(instr));
 
   rv = parseExcludeResultPrefixes(aAttributes, aAttrCount, kNameSpaceID_XSLT);
   NS_ENSURE_SUCCESS(rv, rv);
@@ -1080,23 +1058,21 @@ static nsresult txFnStartLRE(int32_t aNamespaceID, nsAtom* aLocalName,
       continue;
     }
 
-    nsAutoPtr<Expr> avt;
+    UniquePtr<Expr> avt;
     rv = txExprParser::createAVT(attr->mValue, &aState, getter_Transfers(avt));
     NS_ENSURE_SUCCESS(rv, rv);
 
-    instr = new txLREAttribute(attr->mNamespaceID, attr->mLocalName,
-                               attr->mPrefix, std::move(avt));
-    rv = aState.addInstruction(std::move(instr));
-    NS_ENSURE_SUCCESS(rv, rv);
+    instr = MakeUnique<txLREAttribute>(attr->mNamespaceID, attr->mLocalName,
+                                       attr->mPrefix, std::move(avt));
+    aState.addInstruction(std::move(instr));
   }
 
   return NS_OK;
 }
 
 static nsresult txFnEndLRE(txStylesheetCompilerState& aState) {
-  nsAutoPtr<txInstruction> instr(new txEndElement);
-  nsresult rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  UniquePtr<txInstruction> instr(new txEndElement);
+  aState.addInstruction(std::move(instr));
 
   return NS_OK;
 }
@@ -1110,9 +1086,8 @@ static nsresult txFnText(const nsAString& aStr,
                          txStylesheetCompilerState& aState) {
   TX_RETURN_IF_WHITESPACE(aStr, aState);
 
-  nsAutoPtr<txInstruction> instr(new txText(aStr, false));
-  nsresult rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  UniquePtr<txInstruction> instr(new txText(aStr, false));
+  aState.addInstruction(std::move(instr));
 
   return NS_OK;
 }
@@ -1128,15 +1103,11 @@ static nsresult txFnStartApplyImports(int32_t aNamespaceID, nsAtom* aLocalName,
                                       txStylesheetAttr* aAttributes,
                                       int32_t aAttrCount,
                                       txStylesheetCompilerState& aState) {
-  nsresult rv = NS_OK;
+  UniquePtr<txInstruction> instr(new txApplyImportsStart);
+  aState.addInstruction(std::move(instr));
 
-  nsAutoPtr<txInstruction> instr(new txApplyImportsStart);
-  rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  instr = new txApplyImportsEnd;
-  rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  instr = MakeUnique<txApplyImportsEnd>();
+  aState.addInstruction(std::move(instr));
 
   return aState.pushHandlerTable(gTxIgnoreHandler);
 }
@@ -1164,41 +1135,39 @@ static nsresult txFnStartApplyTemplates(int32_t aNamespaceID,
                                         txStylesheetCompilerState& aState) {
   nsresult rv = NS_OK;
 
-  nsAutoPtr<txInstruction> instr(new txPushParams);
-  rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  UniquePtr<txInstruction> instr(new txPushParams);
+  aState.addInstruction(std::move(instr));
 
   txExpandedName mode;
   rv = getQNameAttr(aAttributes, aAttrCount, nsGkAtoms::mode, false, aState,
                     mode);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  instr = new txApplyTemplates(mode);
-  rv = aState.pushObject(instr);
+  instr = MakeUnique<txApplyTemplates>(mode);
+  rv = aState.pushObject(instr.get());
   NS_ENSURE_SUCCESS(rv, rv);
 
-  instr.forget();
+  Unused << instr.release();
 
-  nsAutoPtr<Expr> select;
+  UniquePtr<Expr> select;
   rv = getExprAttr(aAttributes, aAttrCount, nsGkAtoms::select, false, aState,
                    select);
   NS_ENSURE_SUCCESS(rv, rv);
 
   if (!select) {
-    nsAutoPtr<txNodeTest> nt(new txNodeTypeTest(txNodeTypeTest::NODE_TYPE));
-    select = new LocationStep(nt, LocationStep::CHILD_AXIS);
-    nt.forget();
+    UniquePtr<txNodeTest> nt(new txNodeTypeTest(txNodeTypeTest::NODE_TYPE));
+    select = MakeUnique<LocationStep>(nt.release(), LocationStep::CHILD_AXIS);
   }
 
-  nsAutoPtr<txPushNewContext> pushcontext(
+  UniquePtr<txPushNewContext> pushcontext(
       new txPushNewContext(std::move(select)));
-  rv = aState.pushSorter(pushcontext);
+  rv = aState.pushSorter(pushcontext.get());
   NS_ENSURE_SUCCESS(rv, rv);
 
-  rv = aState.pushObject(pushcontext);
+  rv = aState.pushObject(pushcontext.get());
   NS_ENSURE_SUCCESS(rv, rv);
 
-  pushcontext.forget();
+  Unused << pushcontext.release();
 
   return aState.pushHandlerTable(gTxApplyTemplatesHandler);
 }
@@ -1208,25 +1177,22 @@ static nsresult txFnEndApplyTemplates(txStylesheetCompilerState& aState) {
 
   txPushNewContext* pushcontext =
       static_cast<txPushNewContext*>(aState.popObject());
-  nsAutoPtr<txInstruction> instr(pushcontext);  // txPushNewContext
-  nsresult rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  UniquePtr<txInstruction> instr(pushcontext);  // txPushNewContext
+  aState.addInstruction(std::move(instr));
 
   aState.popSorter();
 
-  instr = static_cast<txInstruction*>(aState.popObject());  // txApplyTemplates
-  nsAutoPtr<txLoopNodeSet> loop(new txLoopNodeSet(instr));
-  rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  instr = WrapUnique(
+      static_cast<txInstruction*>(aState.popObject()));  // txApplyTemplates
+  UniquePtr<txLoopNodeSet> loop(new txLoopNodeSet(instr.get()));
+  aState.addInstruction(std::move(instr));
 
-  instr = loop.forget();
-  rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  instr = std::move(loop);
+  aState.addInstruction(std::move(instr));
 
-  instr = new txPopParams;
-  pushcontext->mBailTarget = instr;
-  rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  instr = MakeUnique<txPopParams>();
+  pushcontext->mBailTarget = instr.get();
+  aState.addInstruction(std::move(instr));
 
   return NS_OK;
 }
@@ -1245,25 +1211,24 @@ static nsresult txFnStartAttribute(int32_t aNamespaceID, nsAtom* aLocalName,
                                    txStylesheetCompilerState& aState) {
   nsresult rv = NS_OK;
 
-  nsAutoPtr<txInstruction> instr(new txPushStringHandler(true));
-  rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  UniquePtr<txInstruction> instr(new txPushStringHandler(true));
+  aState.addInstruction(std::move(instr));
 
-  nsAutoPtr<Expr> name;
+  UniquePtr<Expr> name;
   rv = getAVTAttr(aAttributes, aAttrCount, nsGkAtoms::name, true, aState, name);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<Expr> nspace;
+  UniquePtr<Expr> nspace;
   rv = getAVTAttr(aAttributes, aAttrCount, nsGkAtoms::_namespace, false, aState,
                   nspace);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  instr = new txAttribute(std::move(name), std::move(nspace),
-                          aState.mElementContext->mMappings);
-  rv = aState.pushObject(instr);
+  instr = MakeUnique<txAttribute>(std::move(name), std::move(nspace),
+                                  aState.mElementContext->mMappings);
+  rv = aState.pushObject(instr.get());
   NS_ENSURE_SUCCESS(rv, rv);
 
-  instr.forget();
+  Unused << instr.release();
 
   // We need to push the template-handler since the current might be
   // the attributeset-handler
@@ -1272,10 +1237,9 @@ static nsresult txFnStartAttribute(int32_t aNamespaceID, nsAtom* aLocalName,
 
 static nsresult txFnEndAttribute(txStylesheetCompilerState& aState) {
   aState.popHandlerTable();
-  nsAutoPtr<txInstruction> instr(
+  UniquePtr<txInstruction> instr(
       static_cast<txInstruction*>(aState.popObject()));
-  nsresult rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  aState.addInstruction(std::move(instr));
 
   return NS_OK;
 }
@@ -1295,20 +1259,19 @@ static nsresult txFnStartCallTemplate(int32_t aNamespaceID, nsAtom* aLocalName,
                                       txStylesheetCompilerState& aState) {
   nsresult rv = NS_OK;
 
-  nsAutoPtr<txInstruction> instr(new txPushParams);
-  rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  UniquePtr<txInstruction> instr(new txPushParams);
+  aState.addInstruction(std::move(instr));
 
   txExpandedName name;
   rv = getQNameAttr(aAttributes, aAttrCount, nsGkAtoms::name, true, aState,
                     name);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  instr = new txCallTemplate(name);
-  rv = aState.pushObject(instr);
+  instr = MakeUnique<txCallTemplate>(name);
+  rv = aState.pushObject(instr.get());
   NS_ENSURE_SUCCESS(rv, rv);
 
-  instr.forget();
+  Unused << instr.release();
 
   return aState.pushHandlerTable(gTxCallTemplateHandler);
 }
@@ -1317,14 +1280,12 @@ static nsresult txFnEndCallTemplate(txStylesheetCompilerState& aState) {
   aState.popHandlerTable();
 
   // txCallTemplate
-  nsAutoPtr<txInstruction> instr(
+  UniquePtr<txInstruction> instr(
       static_cast<txInstruction*>(aState.popObject()));
-  nsresult rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  aState.addInstruction(std::move(instr));
 
-  instr = new txPopParams;
-  rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  instr = MakeUnique<txPopParams>();
+  aState.addInstruction(std::move(instr));
 
   return NS_OK;
 }
@@ -1356,7 +1317,7 @@ static nsresult txFnStartChoose(int32_t aNamespaceID, nsAtom* aLocalName,
 static nsresult txFnEndChoose(txStylesheetCompilerState& aState) {
   nsresult rv = NS_OK;
   aState.popHandlerTable();
-  txListIterator iter(aState.mChooseGotoList);
+  txListIterator iter(aState.mChooseGotoList.get());
   txGoTo* gotoinstr;
   while ((gotoinstr = static_cast<txGoTo*>(iter.next()))) {
     rv = aState.addGotoTarget(&gotoinstr->mTarget);
@@ -1379,17 +1340,15 @@ static nsresult txFnStartComment(int32_t aNamespaceID, nsAtom* aLocalName,
                                  nsAtom* aPrefix, txStylesheetAttr* aAttributes,
                                  int32_t aAttrCount,
                                  txStylesheetCompilerState& aState) {
-  nsAutoPtr<txInstruction> instr(new txPushStringHandler(true));
-  nsresult rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  UniquePtr<txInstruction> instr(new txPushStringHandler(true));
+  aState.addInstruction(std::move(instr));
 
   return NS_OK;
 }
 
 static nsresult txFnEndComment(txStylesheetCompilerState& aState) {
-  nsAutoPtr<txInstruction> instr(new txComment);
-  nsresult rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  UniquePtr<txInstruction> instr(new txComment);
+  aState.addInstruction(std::move(instr));
 
   return NS_OK;
 }
@@ -1407,13 +1366,12 @@ static nsresult txFnStartCopy(int32_t aNamespaceID, nsAtom* aLocalName,
                               nsAtom* aPrefix, txStylesheetAttr* aAttributes,
                               int32_t aAttrCount,
                               txStylesheetCompilerState& aState) {
-  nsAutoPtr<txCopy> copy(new txCopy);
-  nsresult rv = aState.pushPtr(copy, aState.eCopy);
+  UniquePtr<txCopy> copy(new txCopy);
+  nsresult rv = aState.pushPtr(copy.get(), aState.eCopy);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<txInstruction> instr(copy.forget());
-  rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  UniquePtr<txInstruction> instr(copy.release());
+  aState.addInstruction(std::move(instr));
 
   rv = parseUseAttrSets(aAttributes, aAttrCount, false, aState);
   NS_ENSURE_SUCCESS(rv, rv);
@@ -1422,12 +1380,11 @@ static nsresult txFnStartCopy(int32_t aNamespaceID, nsAtom* aLocalName,
 }
 
 static nsresult txFnEndCopy(txStylesheetCompilerState& aState) {
-  nsAutoPtr<txInstruction> instr(new txEndElement);
-  nsresult rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  UniquePtr<txInstruction> instr(new txEndElement);
+  aState.addInstruction(std::move(instr));
 
   txCopy* copy = static_cast<txCopy*>(aState.popPtr(aState.eCopy));
-  rv = aState.addGotoTarget(&copy->mBailTarget);
+  nsresult rv = aState.addGotoTarget(&copy->mBailTarget);
   NS_ENSURE_SUCCESS(rv, rv);
 
   return NS_OK;
@@ -1444,14 +1401,13 @@ static nsresult txFnStartCopyOf(int32_t aNamespaceID, nsAtom* aLocalName,
                                 txStylesheetCompilerState& aState) {
   nsresult rv = NS_OK;
 
-  nsAutoPtr<Expr> select;
+  UniquePtr<Expr> select;
   rv = getExprAttr(aAttributes, aAttrCount, nsGkAtoms::select, true, aState,
                    select);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<txInstruction> instr(new txCopyOf(std::move(select)));
-  rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  UniquePtr<txInstruction> instr(new txCopyOf(std::move(select)));
+  aState.addInstruction(std::move(instr));
 
   return aState.pushHandlerTable(gTxIgnoreHandler);
 }
@@ -1475,19 +1431,18 @@ static nsresult txFnStartElement(int32_t aNamespaceID, nsAtom* aLocalName,
                                  txStylesheetCompilerState& aState) {
   nsresult rv = NS_OK;
 
-  nsAutoPtr<Expr> name;
+  UniquePtr<Expr> name;
   rv = getAVTAttr(aAttributes, aAttrCount, nsGkAtoms::name, true, aState, name);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<Expr> nspace;
+  UniquePtr<Expr> nspace;
   rv = getAVTAttr(aAttributes, aAttrCount, nsGkAtoms::_namespace, false, aState,
                   nspace);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<txInstruction> instr(new txStartElement(
+  UniquePtr<txInstruction> instr(new txStartElement(
       std::move(name), std::move(nspace), aState.mElementContext->mMappings));
-  rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  aState.addInstruction(std::move(instr));
 
   rv = parseUseAttrSets(aAttributes, aAttrCount, false, aState);
   NS_ENSURE_SUCCESS(rv, rv);
@@ -1496,9 +1451,8 @@ static nsresult txFnStartElement(int32_t aNamespaceID, nsAtom* aLocalName,
 }
 
 static nsresult txFnEndElement(txStylesheetCompilerState& aState) {
-  nsAutoPtr<txInstruction> instr(new txEndElement);
-  nsresult rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  UniquePtr<txInstruction> instr(new txEndElement);
+  aState.addInstruction(std::move(instr));
 
   return NS_OK;
 }
@@ -1541,29 +1495,27 @@ static nsresult txFnStartForEach(int32_t aNamespaceID, nsAtom* aLocalName,
                                  txStylesheetCompilerState& aState) {
   nsresult rv = NS_OK;
 
-  nsAutoPtr<Expr> select;
+  UniquePtr<Expr> select;
   rv = getExprAttr(aAttributes, aAttrCount, nsGkAtoms::select, true, aState,
                    select);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<txPushNewContext> pushcontext(
+  UniquePtr<txPushNewContext> pushcontext(
       new txPushNewContext(std::move(select)));
-  rv = aState.pushPtr(pushcontext, aState.ePushNewContext);
+  rv = aState.pushPtr(pushcontext.get(), aState.ePushNewContext);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  rv = aState.pushSorter(pushcontext);
+  rv = aState.pushSorter(pushcontext.get());
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<txInstruction> instr(pushcontext.forget());
-  rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  UniquePtr<txInstruction> instr(pushcontext.release());
+  aState.addInstruction(std::move(instr));
 
-  instr = new txPushNullTemplateRule;
-  rv = aState.pushPtr(instr, aState.ePushNullTemplateRule);
+  instr = MakeUnique<txPushNullTemplateRule>();
+  rv = aState.pushPtr(instr.get(), aState.ePushNullTemplateRule);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  aState.addInstruction(std::move(instr));
 
   return aState.pushHandlerTable(gTxForEachHandler);
 }
@@ -1575,9 +1527,8 @@ static nsresult txFnEndForEach(txStylesheetCompilerState& aState) {
   txInstruction* pnullrule =
       static_cast<txInstruction*>(aState.popPtr(aState.ePushNullTemplateRule));
 
-  nsAutoPtr<txInstruction> instr(new txLoopNodeSet(pnullrule));
-  nsresult rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  UniquePtr<txInstruction> instr(new txLoopNodeSet(pnullrule));
+  aState.addInstruction(std::move(instr));
 
   aState.popSorter();
   txPushNewContext* pushcontext =
@@ -1618,19 +1569,18 @@ static nsresult txFnStartIf(int32_t aNamespaceID, nsAtom* aLocalName,
                             txStylesheetCompilerState& aState) {
   nsresult rv = NS_OK;
 
-  nsAutoPtr<Expr> test;
+  UniquePtr<Expr> test;
   rv =
       getExprAttr(aAttributes, aAttrCount, nsGkAtoms::test, true, aState, test);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<txConditionalGoto> condGoto(
+  UniquePtr<txConditionalGoto> condGoto(
       new txConditionalGoto(std::move(test), nullptr));
-  rv = aState.pushPtr(condGoto, aState.eConditionalGoto);
+  rv = aState.pushPtr(condGoto.get(), aState.eConditionalGoto);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<txInstruction> instr(condGoto.forget());
-  rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  UniquePtr<txInstruction> instr(condGoto.release());
+  aState.addInstruction(std::move(instr));
 
   return NS_OK;
 }
@@ -1652,29 +1602,27 @@ static nsresult txFnStartMessage(int32_t aNamespaceID, nsAtom* aLocalName,
                                  nsAtom* aPrefix, txStylesheetAttr* aAttributes,
                                  int32_t aAttrCount,
                                  txStylesheetCompilerState& aState) {
-  nsAutoPtr<txInstruction> instr(new txPushStringHandler(false));
-  nsresult rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  UniquePtr<txInstruction> instr(new txPushStringHandler(false));
+  aState.addInstruction(std::move(instr));
 
   txThreeState term;
-  rv = getYesNoAttr(aAttributes, aAttrCount, nsGkAtoms::terminate, false,
-                    aState, term);
+  nsresult rv = getYesNoAttr(aAttributes, aAttrCount, nsGkAtoms::terminate,
+                             false, aState, term);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  instr = new txMessage(term == eTrue);
-  rv = aState.pushObject(instr);
+  instr = MakeUnique<txMessage>(term == eTrue);
+  rv = aState.pushObject(instr.get());
   NS_ENSURE_SUCCESS(rv, rv);
 
-  instr.forget();
+  Unused << instr.release();
 
   return NS_OK;
 }
 
 static nsresult txFnEndMessage(txStylesheetCompilerState& aState) {
-  nsAutoPtr<txInstruction> instr(
+  UniquePtr<txInstruction> instr(
       static_cast<txInstruction*>(aState.popObject()));
-  nsresult rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  aState.addInstruction(std::move(instr));
 
   return NS_OK;
 }
@@ -1704,52 +1652,51 @@ static nsresult txFnStartNumber(int32_t aNamespaceID, nsAtom* aLocalName,
     return NS_ERROR_XSLT_PARSE_FAILURE;
   }
 
-  nsAutoPtr<txPattern> count;
+  UniquePtr<txPattern> count;
   rv = getPatternAttr(aAttributes, aAttrCount, nsGkAtoms::count, false, aState,
                       count);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<txPattern> from;
+  UniquePtr<txPattern> from;
   rv = getPatternAttr(aAttributes, aAttrCount, nsGkAtoms::from, false, aState,
                       from);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<Expr> value;
+  UniquePtr<Expr> value;
   rv = getExprAttr(aAttributes, aAttrCount, nsGkAtoms::value, false, aState,
                    value);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<Expr> format;
+  UniquePtr<Expr> format;
   rv = getAVTAttr(aAttributes, aAttrCount, nsGkAtoms::format, false, aState,
                   format);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<Expr> lang;
+  UniquePtr<Expr> lang;
   rv =
       getAVTAttr(aAttributes, aAttrCount, nsGkAtoms::lang, false, aState, lang);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<Expr> letterValue;
+  UniquePtr<Expr> letterValue;
   rv = getAVTAttr(aAttributes, aAttrCount, nsGkAtoms::letterValue, false,
                   aState, letterValue);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<Expr> groupingSeparator;
+  UniquePtr<Expr> groupingSeparator;
   rv = getAVTAttr(aAttributes, aAttrCount, nsGkAtoms::groupingSeparator, false,
                   aState, groupingSeparator);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<Expr> groupingSize;
+  UniquePtr<Expr> groupingSize;
   rv = getAVTAttr(aAttributes, aAttrCount, nsGkAtoms::groupingSize, false,
                   aState, groupingSize);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<txInstruction> instr(
+  UniquePtr<txInstruction> instr(
       new txNumber(level, std::move(count), std::move(from), std::move(value),
                    std::move(format), std::move(groupingSeparator),
                    std::move(groupingSize)));
-  rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  aState.addInstruction(std::move(instr));
 
   return aState.pushHandlerTable(gTxIgnoreHandler);
 }
@@ -1800,22 +1747,21 @@ static nsresult txFnStartParam(int32_t aNamespaceID, nsAtom* aLocalName,
                     name);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<txCheckParam> checkParam(new txCheckParam(name));
+  UniquePtr<txCheckParam> checkParam(new txCheckParam(name));
   NS_ENSURE_SUCCESS(rv, rv);
 
-  rv = aState.pushPtr(checkParam, aState.eCheckParam);
+  rv = aState.pushPtr(checkParam.get(), aState.eCheckParam);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<txInstruction> instr(checkParam.forget());
-  rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  UniquePtr<txInstruction> instr(checkParam.release());
+  aState.addInstruction(std::move(instr));
 
-  nsAutoPtr<Expr> select;
+  UniquePtr<Expr> select;
   rv = getExprAttr(aAttributes, aAttrCount, nsGkAtoms::select, false, aState,
                    select);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<txSetVariable> var(new txSetVariable(name, std::move(select)));
+  UniquePtr<txSetVariable> var(new txSetVariable(name, std::move(select)));
   if (var->mValue) {
     // XXX should be gTxErrorHandler?
     rv = aState.pushHandlerTable(gTxIgnoreHandler);
@@ -1825,31 +1771,30 @@ static nsresult txFnStartParam(int32_t aNamespaceID, nsAtom* aLocalName,
     NS_ENSURE_SUCCESS(rv, rv);
   }
 
-  rv = aState.pushObject(var);
+  rv = aState.pushObject(var.get());
   NS_ENSURE_SUCCESS(rv, rv);
 
-  var.forget();
+  Unused << var.release();
 
   return NS_OK;
 }
 
 static nsresult txFnEndParam(txStylesheetCompilerState& aState) {
-  nsAutoPtr<txSetVariable> var(static_cast<txSetVariable*>(aState.popObject()));
+  UniquePtr<txSetVariable> var(static_cast<txSetVariable*>(aState.popObject()));
   txHandlerTable* prev = aState.mHandlerTable;
   aState.popHandlerTable();
 
   if (prev == gTxVariableHandler) {
     // No children were found.
     NS_ASSERTION(!var->mValue, "There shouldn't be a select-expression here");
-    var->mValue = new txLiteralExpr(EmptyString());
+    var->mValue = MakeUnique<txLiteralExpr>(EmptyString());
   }
 
   nsresult rv = aState.addVariable(var->mName);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<txInstruction> instr(var.forget());
-  rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  UniquePtr<txInstruction> instr(var.release());
+  aState.addInstruction(std::move(instr));
 
   txCheckParam* checkParam =
       static_cast<txCheckParam*>(aState.popPtr(aState.eCheckParam));
@@ -1869,28 +1814,27 @@ static nsresult txFnStartPI(int32_t aNamespaceID, nsAtom* aLocalName,
                             nsAtom* aPrefix, txStylesheetAttr* aAttributes,
                             int32_t aAttrCount,
                             txStylesheetCompilerState& aState) {
-  nsAutoPtr<txInstruction> instr(new txPushStringHandler(true));
-  nsresult rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  UniquePtr<txInstruction> instr(new txPushStringHandler(true));
+  aState.addInstruction(std::move(instr));
 
-  nsAutoPtr<Expr> name;
-  rv = getAVTAttr(aAttributes, aAttrCount, nsGkAtoms::name, true, aState, name);
+  UniquePtr<Expr> name;
+  nsresult rv =
+      getAVTAttr(aAttributes, aAttrCount, nsGkAtoms::name, true, aState, name);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  instr = new txProcessingInstruction(std::move(name));
-  rv = aState.pushObject(instr);
+  instr = MakeUnique<txProcessingInstruction>(std::move(name));
+  rv = aState.pushObject(instr.get());
   NS_ENSURE_SUCCESS(rv, rv);
 
-  instr.forget();
+  Unused << instr.release();
 
   return NS_OK;
 }
 
 static nsresult txFnEndPI(txStylesheetCompilerState& aState) {
-  nsAutoPtr<txInstruction> instr(
+  UniquePtr<txInstruction> instr(
       static_cast<txInstruction*>(aState.popObject()));
-  nsresult rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  aState.addInstruction(std::move(instr));
 
   return NS_OK;
 }
@@ -1906,35 +1850,32 @@ static nsresult txFnStartSort(int32_t aNamespaceID, nsAtom* aLocalName,
                               txStylesheetCompilerState& aState) {
   nsresult rv = NS_OK;
 
-  nsAutoPtr<Expr> select;
+  UniquePtr<Expr> select;
   rv = getExprAttr(aAttributes, aAttrCount, nsGkAtoms::select, false, aState,
                    select);
   NS_ENSURE_SUCCESS(rv, rv);
 
   if (!select) {
-    nsAutoPtr<txNodeTest> nt(new txNodeTypeTest(txNodeTypeTest::NODE_TYPE));
-
-    select = new LocationStep(nt, LocationStep::SELF_AXIS);
-
-    nt.forget();
+    UniquePtr<txNodeTest> nt(new txNodeTypeTest(txNodeTypeTest::NODE_TYPE));
+    select = MakeUnique<LocationStep>(nt.release(), LocationStep::SELF_AXIS);
   }
 
-  nsAutoPtr<Expr> lang;
+  UniquePtr<Expr> lang;
   rv =
       getAVTAttr(aAttributes, aAttrCount, nsGkAtoms::lang, false, aState, lang);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<Expr> dataType;
+  UniquePtr<Expr> dataType;
   rv = getAVTAttr(aAttributes, aAttrCount, nsGkAtoms::dataType, false, aState,
                   dataType);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<Expr> order;
+  UniquePtr<Expr> order;
   rv = getAVTAttr(aAttributes, aAttrCount, nsGkAtoms::order, false, aState,
                   order);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<Expr> caseOrder;
+  UniquePtr<Expr> caseOrder;
   rv = getAVTAttr(aAttributes, aAttrCount, nsGkAtoms::caseOrder, false, aState,
                   caseOrder);
   NS_ENSURE_SUCCESS(rv, rv);
@@ -1983,9 +1924,8 @@ static nsresult txFnEndText(txStylesheetCompilerState& aState) {
 
 static nsresult txFnTextText(const nsAString& aStr,
                              txStylesheetCompilerState& aState) {
-  nsAutoPtr<txInstruction> instr(new txText(aStr, aState.mDOE));
-  nsresult rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  UniquePtr<txInstruction> instr(new txText(aStr, aState.mDOE));
+  aState.addInstruction(std::move(instr));
 
   return NS_OK;
 }
@@ -2006,15 +1946,14 @@ static nsresult txFnStartValueOf(int32_t aNamespaceID, nsAtom* aLocalName,
                     false, aState, doe);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<Expr> select;
+  UniquePtr<Expr> select;
   rv = getExprAttr(aAttributes, aAttrCount, nsGkAtoms::select, true, aState,
                    select);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<txInstruction> instr(
+  UniquePtr<txInstruction> instr(
       new txValueOf(std::move(select), doe == eTrue));
-  rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  aState.addInstruction(std::move(instr));
 
   return aState.pushHandlerTable(gTxIgnoreHandler);
 }
@@ -2043,12 +1982,12 @@ static nsresult txFnStartVariable(int32_t aNamespaceID, nsAtom* aLocalName,
                     name);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<Expr> select;
+  UniquePtr<Expr> select;
   rv = getExprAttr(aAttributes, aAttrCount, nsGkAtoms::select, false, aState,
                    select);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<txSetVariable> var(new txSetVariable(name, std::move(select)));
+  UniquePtr<txSetVariable> var(new txSetVariable(name, std::move(select)));
   if (var->mValue) {
     // XXX should be gTxErrorHandler?
     rv = aState.pushHandlerTable(gTxIgnoreHandler);
@@ -2058,16 +1997,16 @@ static nsresult txFnStartVariable(int32_t aNamespaceID, nsAtom* aLocalName,
     NS_ENSURE_SUCCESS(rv, rv);
   }
 
-  rv = aState.pushObject(var);
+  rv = aState.pushObject(var.get());
   NS_ENSURE_SUCCESS(rv, rv);
 
-  var.forget();
+  Unused << var.release();
 
   return NS_OK;
 }
 
 static nsresult txFnEndVariable(txStylesheetCompilerState& aState) {
-  nsAutoPtr<txSetVariable> var(static_cast<txSetVariable*>(aState.popObject()));
+  UniquePtr<txSetVariable> var(static_cast<txSetVariable*>(aState.popObject()));
 
   txHandlerTable* prev = aState.mHandlerTable;
   aState.popHandlerTable();
@@ -2075,15 +2014,14 @@ static nsresult txFnEndVariable(txStylesheetCompilerState& aState) {
   if (prev == gTxVariableHandler) {
     // No children were found.
     NS_ASSERTION(!var->mValue, "There shouldn't be a select-expression here");
-    var->mValue = new txLiteralExpr(EmptyString());
+    var->mValue = MakeUnique<txLiteralExpr>(EmptyString());
   }
 
   nsresult rv = aState.addVariable(var->mName);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<txInstruction> instr(var.forget());
-  rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  UniquePtr<txInstruction> instr(var.release());
+  aState.addInstruction(std::move(instr));
 
   return NS_OK;
 }
@@ -2093,9 +2031,8 @@ static nsresult txFnStartElementStartRTF(int32_t aNamespaceID,
                                          txStylesheetAttr* aAttributes,
                                          int32_t aAttrCount,
                                          txStylesheetCompilerState& aState) {
-  nsAutoPtr<txInstruction> instr(new txPushRTFHandler);
-  nsresult rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  UniquePtr<txInstruction> instr(new txPushRTFHandler);
+  aState.addInstruction(std::move(instr));
 
   aState.mHandlerTable = gTxTemplateHandler;
 
@@ -2106,9 +2043,8 @@ static nsresult txFnTextStartRTF(const nsAString& aStr,
                                  txStylesheetCompilerState& aState) {
   TX_RETURN_IF_WHITESPACE(aStr, aState);
 
-  nsAutoPtr<txInstruction> instr(new txPushRTFHandler);
-  nsresult rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  UniquePtr<txInstruction> instr(new txPushRTFHandler);
+  aState.addInstruction(std::move(instr));
 
   aState.mHandlerTable = gTxTemplateHandler;
 
@@ -2126,36 +2062,33 @@ static nsresult txFnStartWhen(int32_t aNamespaceID, nsAtom* aLocalName,
                               txStylesheetCompilerState& aState) {
   nsresult rv = NS_OK;
 
-  nsAutoPtr<Expr> test;
+  UniquePtr<Expr> test;
   rv =
       getExprAttr(aAttributes, aAttrCount, nsGkAtoms::test, true, aState, test);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<txConditionalGoto> condGoto(
+  UniquePtr<txConditionalGoto> condGoto(
       new txConditionalGoto(std::move(test), nullptr));
-  rv = aState.pushPtr(condGoto, aState.eConditionalGoto);
+  rv = aState.pushPtr(condGoto.get(), aState.eConditionalGoto);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<txInstruction> instr(condGoto.forget());
-  rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  UniquePtr<txInstruction> instr(condGoto.release());
+  aState.addInstruction(std::move(instr));
 
   return aState.pushHandlerTable(gTxTemplateHandler);
 }
 
 static nsresult txFnEndWhen(txStylesheetCompilerState& aState) {
   aState.popHandlerTable();
-  nsAutoPtr<txGoTo> gotoinstr(new txGoTo(nullptr));
-  nsresult rv = aState.mChooseGotoList->add(gotoinstr);
-  NS_ENSURE_SUCCESS(rv, rv);
+  UniquePtr<txGoTo> gotoinstr(new txGoTo(nullptr));
+  aState.mChooseGotoList->add(gotoinstr.get());
 
-  nsAutoPtr<txInstruction> instr(gotoinstr.forget());
-  rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  UniquePtr<txInstruction> instr(gotoinstr.release());
+  aState.addInstruction(std::move(instr));
 
   txConditionalGoto* condGoto =
       static_cast<txConditionalGoto*>(aState.popPtr(aState.eConditionalGoto));
-  rv = aState.addGotoTarget(&condGoto->mTarget);
+  nsresult rv = aState.addGotoTarget(&condGoto->mTarget);
   NS_ENSURE_SUCCESS(rv, rv);
 
   return NS_OK;
@@ -2180,12 +2113,12 @@ static nsresult txFnStartWithParam(int32_t aNamespaceID, nsAtom* aLocalName,
                     name);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<Expr> select;
+  UniquePtr<Expr> select;
   rv = getExprAttr(aAttributes, aAttrCount, nsGkAtoms::select, false, aState,
                    select);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  nsAutoPtr<txSetParam> var(new txSetParam(name, std::move(select)));
+  UniquePtr<txSetParam> var(new txSetParam(name, std::move(select)));
   if (var->mValue) {
     // XXX should be gTxErrorHandler?
     rv = aState.pushHandlerTable(gTxIgnoreHandler);
@@ -2195,28 +2128,27 @@ static nsresult txFnStartWithParam(int32_t aNamespaceID, nsAtom* aLocalName,
     NS_ENSURE_SUCCESS(rv, rv);
   }
 
-  rv = aState.pushObject(var);
+  rv = aState.pushObject(var.get());
   NS_ENSURE_SUCCESS(rv, rv);
 
-  var.forget();
+  Unused << var.release();
 
   return NS_OK;
 }
 
 static nsresult txFnEndWithParam(txStylesheetCompilerState& aState) {
-  nsAutoPtr<txSetParam> var(static_cast<txSetParam*>(aState.popObject()));
+  UniquePtr<txSetParam> var(static_cast<txSetParam*>(aState.popObject()));
   txHandlerTable* prev = aState.mHandlerTable;
   aState.popHandlerTable();
 
   if (prev == gTxVariableHandler) {
     // No children were found.
     NS_ASSERTION(!var->mValue, "There shouldn't be a select-expression here");
-    var->mValue = new txLiteralExpr(EmptyString());
+    var->mValue = MakeUnique<txLiteralExpr>(EmptyString());
   }
 
-  nsAutoPtr<txInstruction> instr(var.forget());
-  nsresult rv = aState.addInstruction(std::move(instr));
-  NS_ENSURE_SUCCESS(rv, rv);
+  UniquePtr<txInstruction> instr(var.release());
+  aState.addInstruction(std::move(instr));
 
   return NS_OK;
 }
@@ -2249,9 +2181,8 @@ static nsresult txFnEndUnknownInstruction(txStylesheetCompilerState& aState) {
   aState.popHandlerTable();
 
   if (aState.mSearchingForFallback) {
-    nsAutoPtr<txInstruction> instr(new txErrorInstruction());
-    nsresult rv = aState.addInstruction(std::move(instr));
-    NS_ENSURE_SUCCESS(rv, rv);
+    UniquePtr<txInstruction> instr(new txErrorInstruction());
+    aState.addInstruction(std::move(instr));
   }
 
   aState.mSearchingForFallback = false;
diff --git a/dom/xslt/xslt/txStylesheetCompiler.cpp b/dom/xslt/xslt/txStylesheetCompiler.cpp
index ab0400ad60..f02864732d 100644
--- a/dom/xslt/xslt/txStylesheetCompiler.cpp
+++ b/dom/xslt/xslt/txStylesheetCompiler.cpp
@@ -2,25 +2,26 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+#include "txStylesheetCompiler.h"
+
+#include <utility>
+
 #include "mozilla/ArrayUtils.h"
-#include "mozilla/Move.h"
 #include "mozilla/UniquePtr.h"
-
-#include "txStylesheetCompiler.h"
-#include "txStylesheetCompileHandlers.h"
 #include "nsGkAtoms.h"
-#include "txURIUtils.h"
+#include "nsServiceManagerUtils.h"
+#include "nsTArray.h"
 #include "nsWhitespaceTokenizer.h"
-#include "txStylesheet.h"
-#include "txInstructions.h"
-#include "txToplevelItems.h"
 #include "txExprParser.h"
+#include "txInstructions.h"
 #include "txLog.h"
 #include "txPatternParser.h"
 #include "txStringUtils.h"
+#include "txStylesheet.h"
+#include "txStylesheetCompileHandlers.h"
+#include "txToplevelItems.h"
+#include "txURIUtils.h"
 #include "txXSLTFunctions.h"
-#include "nsServiceManagerUtils.h"
-#include "nsTArray.h"
 
 using namespace mozilla;
 using mozilla::dom::ReferrerPolicy;
@@ -293,9 +294,8 @@ nsresult txStylesheetCompiler::endElement() {
   for (i = mInScopeVariables.Length() - 1; i >= 0; --i) {
     txInScopeVariable* var = mInScopeVariables[i];
     if (!--(var->mLevel)) {
-      nsAutoPtr<txInstruction> instr(new txRemoveVariable(var->mName));
-      rv = addInstruction(std::move(instr));
-      NS_ENSURE_SUCCESS(rv, rv);
+      UniquePtr<txInstruction> instr(new txRemoveVariable(var->mName));
+      addInstruction(std::move(instr));
 
       mInScopeVariables.RemoveElementAt(i);
       delete var;
@@ -309,7 +309,7 @@ nsresult txStylesheetCompiler::endElement() {
 
   if (!--mElementContext->mDepth) {
     // this will delete the old object
-    mElementContext = static_cast<txElementContext*>(popObject());
+    mElementContext = WrapUnique(static_cast<txElementContext*>(popObject()));
   }
 
   return NS_OK;
@@ -416,11 +416,11 @@ nsresult txStylesheetCompiler::ensureNewElementContext() {
     return NS_OK;
   }
 
-  nsAutoPtr<txElementContext> context(new txElementContext(*mElementContext));
-  nsresult rv = pushObject(mElementContext);
+  UniquePtr<txElementContext> context(new txElementContext(*mElementContext));
+  nsresult rv = pushObject(mElementContext.get());
   NS_ENSURE_SUCCESS(rv, rv);
 
-  mElementContext.forget();
+  Unused << mElementContext.release();
   mElementContext = std::move(context);
 
   return NS_OK;
@@ -508,7 +508,7 @@ nsresult txStylesheetCompilerState::init(const nsAString& aStylesheetURI,
     mIsTopCompiler = true;
   }
 
-  mElementContext = new txElementContext(aStylesheetURI);
+  mElementContext = MakeUnique<txElementContext>(aStylesheetURI);
   NS_ENSURE_TRUE(mElementContext->mMappings, NS_ERROR_OUT_OF_MEMORY);
 
   // Push the "old" txElementContext
@@ -556,18 +556,18 @@ void txStylesheetCompilerState::popSorter() {
 }
 
 nsresult txStylesheetCompilerState::pushChooseGotoList() {
-  nsresult rv = pushObject(mChooseGotoList);
+  nsresult rv = pushObject(mChooseGotoList.get());
   NS_ENSURE_SUCCESS(rv, rv);
 
-  mChooseGotoList.forget();
-  mChooseGotoList = new txList;
+  Unused << mChooseGotoList.release();
+  mChooseGotoList = MakeUnique<txList>();
 
   return NS_OK;
 }
 
 void txStylesheetCompilerState::popChooseGotoList() {
   // this will delete the old value
-  mChooseGotoList = static_cast<txList*>(popObject());
+  mChooseGotoList = WrapUnique(static_cast<txList*>(popObject()));
 }
 
 nsresult txStylesheetCompilerState::pushObject(txObject* aObject) {
@@ -607,15 +607,15 @@ void* txStylesheetCompilerState::popPtr(enumStackType aType) {
   return value;
 }
 
-nsresult txStylesheetCompilerState::addToplevelItem(txToplevelItem* aItem) {
-  return mToplevelIterator.addBefore(aItem);
+void txStylesheetCompilerState::addToplevelItem(txToplevelItem* aItem) {
+  mToplevelIterator.addBefore(aItem);
 }
 
 nsresult txStylesheetCompilerState::openInstructionContainer(
     txInstructionContainer* aContainer) {
   MOZ_ASSERT(!mNextInstrPtr, "can't nest instruction-containers");
 
-  mNextInstrPtr = aContainer->mFirstInstruction.StartAssignment();
+  mNextInstrPtr = &aContainer->mFirstInstruction;
   return NS_OK;
 }
 
@@ -625,22 +625,20 @@ void txStylesheetCompilerState::closeInstructionContainer() {
   mNextInstrPtr = 0;
 }
 
-nsresult txStylesheetCompilerState::addInstruction(
-    nsAutoPtr<txInstruction>&& aInstruction) {
+void txStylesheetCompilerState::addInstruction(
+    UniquePtr<txInstruction>&& aInstruction) {
   MOZ_ASSERT(mNextInstrPtr, "adding instruction outside container");
 
-  txInstruction* newInstr = aInstruction;
+  txInstruction* newInstr = aInstruction.get();
 
-  *mNextInstrPtr = aInstruction.forget();
-  mNextInstrPtr = newInstr->mNext.StartAssignment();
+  *mNextInstrPtr = std::move(aInstruction);
+  mNextInstrPtr = &newInstr->mNext;
 
   uint32_t i, count = mGotoTargetPointers.Length();
   for (i = 0; i < count; ++i) {
     *mGotoTargetPointers[i] = newInstr;
   }
   mGotoTargetPointers.Clear();
-
-  return NS_OK;
 }
 
 nsresult txStylesheetCompilerState::loadIncludedStylesheet(
@@ -653,13 +651,10 @@ nsresult txStylesheetCompilerState::loadIncludedStylesheet(
   }
   NS_ENSURE_TRUE(mObserver, NS_ERROR_NOT_IMPLEMENTED);
 
-  nsAutoPtr<txToplevelItem> item(new txDummyItem);
+  UniquePtr<txToplevelItem> item(new txDummyItem);
   NS_ENSURE_TRUE(item, NS_ERROR_OUT_OF_MEMORY);
 
-  nsresult rv = mToplevelIterator.addBefore(item);
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  item.forget();
+  mToplevelIterator.addBefore(item.release());
 
   // step back to the dummy-item
   mToplevelIterator.previous();
@@ -677,7 +672,8 @@ nsresult txStylesheetCompilerState::loadIncludedStylesheet(
   // pretended earlier.
   mChildCompilerList.AppendElement(compiler);
 
-  rv = mObserver->loadURI(aURI, mStylesheetURI, mReferrerPolicy, compiler);
+  nsresult rv =
+      mObserver->loadURI(aURI, mStylesheetURI, mReferrerPolicy, compiler);
   if (NS_FAILED(rv)) {
     mChildCompilerList.RemoveElement(compiler);
   }
@@ -838,7 +834,7 @@ extern bool TX_XSLTFunctionAvailable(nsAtom* aName, int32_t aNameSpaceID) {
       new txStylesheetCompiler(EmptyString(), ReferrerPolicy::_empty, nullptr);
   NS_ENSURE_TRUE(compiler, false);
 
-  nsAutoPtr<FunctionCall> fnCall;
+  UniquePtr<FunctionCall> fnCall;
 
   return NS_SUCCEEDED(
       findFunction(aName, aNameSpaceID, compiler, getter_Transfers(fnCall)));
diff --git a/dom/xslt/xslt/txStylesheetCompiler.h b/dom/xslt/xslt/txStylesheetCompiler.h
index 74e6520439..17a1bdcac1 100644
--- a/dom/xslt/xslt/txStylesheetCompiler.h
+++ b/dom/xslt/xslt/txStylesheetCompiler.h
@@ -6,11 +6,11 @@
 #define TRANSFRMX_TXSTYLESHEETCOMPILER_H
 
 #include "mozilla/Attributes.h"
+#include "mozilla/UniquePtr.h"
 #include "txStack.h"
 #include "txXSLTPatterns.h"
 #include "txExpr.h"
 #include "txIXPathContext.h"
-#include "nsAutoPtr.h"
 #include "txStylesheet.h"
 #include "nsTArray.h"
 
@@ -98,10 +98,10 @@ class txStylesheetCompilerState : public txIParseContext {
   void* popPtr(enumStackType aType);
 
   // stylesheet functions
-  nsresult addToplevelItem(txToplevelItem* aItem);
+  void addToplevelItem(txToplevelItem* aItem);
   nsresult openInstructionContainer(txInstructionContainer* aContainer);
   void closeInstructionContainer();
-  nsresult addInstruction(nsAutoPtr<txInstruction>&& aInstruction);
+  void addInstruction(mozilla::UniquePtr<txInstruction>&& aInstruction);
   nsresult loadIncludedStylesheet(const nsAString& aURI);
   nsresult loadImportedStylesheet(const nsAString& aURI,
                                   txStylesheet::ImportFrame* aFrame);
@@ -133,9 +133,9 @@ class txStylesheetCompilerState : public txIParseContext {
 
   RefPtr<txStylesheet> mStylesheet;
   txHandlerTable* mHandlerTable;
-  nsAutoPtr<txElementContext> mElementContext;
+  mozilla::UniquePtr<txElementContext> mElementContext;
   txPushNewContext* mSorter;
-  nsAutoPtr<txList> mChooseGotoList;
+  mozilla::UniquePtr<txList> mChooseGotoList;
   bool mDOE;
   bool mSearchingForFallback;
   uint16_t mDisAllowed;
@@ -155,7 +155,7 @@ class txStylesheetCompilerState : public txIParseContext {
   nsTArray<enumStackType> mTypeStack;
 
  private:
-  txInstruction** mNextInstrPtr;
+  mozilla::UniquePtr<txInstruction>* mNextInstrPtr;
   txListIterator mToplevelIterator;
   nsTArray<txInstruction**> mGotoTargetPointers;
   ReferrerPolicy mReferrerPolicy;
diff --git a/dom/xslt/xslt/txToplevelItems.cpp b/dom/xslt/xslt/txToplevelItems.cpp
index 6d2e0f0151..8e93316c88 100644
--- a/dom/xslt/xslt/txToplevelItems.cpp
+++ b/dom/xslt/xslt/txToplevelItems.cpp
@@ -4,11 +4,14 @@
 
 #include "txToplevelItems.h"
 
-#include "mozilla/Move.h"
-#include "txStylesheet.h"
+#include <utility>
+
 #include "txInstructions.h"
+#include "txStylesheet.h"
 #include "txXSLTPatterns.h"
 
+using mozilla::UniquePtr;
+
 TX_IMPL_GETTYPE(txAttributeSetItem, txToplevelItem::attributeSet)
 TX_IMPL_GETTYPE(txImportItem, txToplevelItem::import)
 TX_IMPL_GETTYPE(txOutputItem, txToplevelItem::output)
@@ -33,7 +36,7 @@ nsresult txStripSpaceItem::addStripSpaceTest(
 
 TX_IMPL_GETTYPE(txTemplateItem, txToplevelItem::templ)
 
-txTemplateItem::txTemplateItem(nsAutoPtr<txPattern>&& aMatch,
+txTemplateItem::txTemplateItem(UniquePtr<txPattern>&& aMatch,
                                const txExpandedName& aName,
                                const txExpandedName& aMode, double aPrio)
     : mMatch(std::move(aMatch)), mName(aName), mMode(aMode), mPrio(aPrio) {}
@@ -41,5 +44,5 @@ txTemplateItem::txTemplateItem(nsAutoPtr<txPattern>&& aMatch,
 TX_IMPL_GETTYPE(txVariableItem, txToplevelItem::variable)
 
 txVariableItem::txVariableItem(const txExpandedName& aName,
-                               nsAutoPtr<Expr>&& aValue, bool aIsParam)
+                               UniquePtr<Expr>&& aValue, bool aIsParam)
     : mName(aName), mValue(std::move(aValue)), mIsParam(aIsParam) {}
diff --git a/dom/xslt/xslt/txToplevelItems.h b/dom/xslt/xslt/txToplevelItems.h
index ced6037006..5141d6a5ef 100644
--- a/dom/xslt/xslt/txToplevelItems.h
+++ b/dom/xslt/xslt/txToplevelItems.h
@@ -39,7 +39,7 @@ class txToplevelItem {
 
 class txInstructionContainer : public txToplevelItem {
  public:
-  nsAutoPtr<txInstruction> mFirstInstruction;
+  mozilla::UniquePtr<txInstruction> mFirstInstruction;
 };
 
 // xsl:attribute-set
@@ -57,7 +57,7 @@ class txImportItem : public txToplevelItem {
  public:
   TX_DECL_TOPLEVELITEM
 
-  nsAutoPtr<txStylesheet::ImportFrame> mFrame;
+  mozilla::UniquePtr<txStylesheet::ImportFrame> mFrame;
 };
 
 // xsl:output
@@ -89,12 +89,13 @@ class txStripSpaceItem : public txToplevelItem {
 // xsl:template
 class txTemplateItem : public txInstructionContainer {
  public:
-  txTemplateItem(nsAutoPtr<txPattern>&& aMatch, const txExpandedName& aName,
-                 const txExpandedName& aMode, double aPrio);
+  txTemplateItem(mozilla::UniquePtr<txPattern>&& aMatch,
+                 const txExpandedName& aName, const txExpandedName& aMode,
+                 double aPrio);
 
   TX_DECL_TOPLEVELITEM
 
-  nsAutoPtr<txPattern> mMatch;
+  mozilla::UniquePtr<txPattern> mMatch;
   txExpandedName mName;
   txExpandedName mMode;
   double mPrio;
@@ -103,13 +104,13 @@ class txTemplateItem : public txInstructionContainer {
 // xsl:variable at top level
 class txVariableItem : public txInstructionContainer {
  public:
-  txVariableItem(const txExpandedName& aName, nsAutoPtr<Expr>&& aValue,
+  txVariableItem(const txExpandedName& aName, mozilla::UniquePtr<Expr>&& aValue,
                  bool aIsParam);
 
   TX_DECL_TOPLEVELITEM
 
   txExpandedName mName;
-  nsAutoPtr<Expr> mValue;
+  mozilla::UniquePtr<Expr> mValue;
   bool mIsParam;
 };
 
diff --git a/dom/xslt/xslt/txUnknownHandler.cpp b/dom/xslt/xslt/txUnknownHandler.cpp
index 71775b36ff..9b96ce0512 100644
--- a/dom/xslt/xslt/txUnknownHandler.cpp
+++ b/dom/xslt/xslt/txUnknownHandler.cpp
@@ -4,11 +4,15 @@
 
 #include "txUnknownHandler.h"
 
-#include "mozilla/Move.h"
+#include <utility>
+
+#include "nsGkAtoms.h"
 #include "txExecutionState.h"
 #include "txStringUtils.h"
 #include "txStylesheet.h"
-#include "nsGkAtoms.h"
+
+using mozilla::UniquePtr;
+using mozilla::WrapUnique;
 
 txUnknownHandler::txUnknownHandler(txExecutionState* aEs)
     : mEs(aEs), mFlushed(false) {
@@ -150,23 +154,23 @@ nsresult txUnknownHandler::createHandlerAndFlush(bool aHTMLRoot,
     format.mMethod = aHTMLRoot ? eHTMLOutput : eXMLOutput;
   }
 
-  nsAutoPtr<txAXMLEventHandler> handler;
+  UniquePtr<txAXMLEventHandler> handler;
   nsresult rv = mEs->mOutputHandlerFactory->createHandlerWith(
       &format, aName, aNsID, getter_Transfers(handler));
   NS_ENSURE_SUCCESS(rv, rv);
 
-  mEs->mOutputHandler = handler;
-  mEs->mResultHandler = handler.forget();
+  mEs->mOutputHandler = handler.get();
+  mEs->mResultHandler = handler.release();
   // Let the executionstate delete us. We need to stay alive because we might
   // need to forward hooks to mEs->mResultHandler if someone is currently
   // flushing a buffer to mEs->mResultHandler.
-  mEs->mObsoleteHandler = this;
+  mEs->mObsoleteHandler = WrapUnique(this);
 
   mFlushed = true;
 
   // Let go of out buffer as soon as we're done flushing it, we're not going
   // to need it anymore from this point on (all hooks get forwarded to
   // mEs->mResultHandler.
-  nsAutoPtr<txResultBuffer> buffer(std::move(mBuffer));
+  UniquePtr<txResultBuffer> buffer(std::move(mBuffer));
   return buffer->flushToHandler(mEs->mResultHandler);
 }
diff --git a/dom/xslt/xslt/txXPathResultComparator.cpp b/dom/xslt/xslt/txXPathResultComparator.cpp
index c07f9cb58e..0a731992ae 100644
--- a/dom/xslt/xslt/txXPathResultComparator.cpp
+++ b/dom/xslt/xslt/txXPathResultComparator.cpp
@@ -6,9 +6,12 @@
 
 #include "txXPathResultComparator.h"
 #include "txExpr.h"
+#include "nsComponentManagerUtils.h"
 #include "txCore.h"
 #include "nsCollationCID.h"
 
+using namespace mozilla;
+
 #define kAscending (1 << 0)
 #define kUpperFirst (1 << 1)
 
@@ -44,29 +47,29 @@ nsresult txResultStringComparator::init(const nsString& aLanguage) {
 nsresult txResultStringComparator::createSortableValue(Expr* aExpr,
                                                        txIEvalContext* aContext,
                                                        txObject*& aResult) {
-  nsAutoPtr<StringValue> val(new StringValue);
+  UniquePtr<StringValue> val(new StringValue);
   if (!val) {
     return NS_ERROR_OUT_OF_MEMORY;
   }
 
   if (!mCollation) return NS_ERROR_FAILURE;
 
-  val->mCaseKey = new nsString;
-  nsString& nsCaseKey = *(nsString*)val->mCaseKey;
+  val->mCaseKeyString = MakeUnique<nsString>();
+  nsString& nsCaseKey = *val->mCaseKeyString;
   nsresult rv = aExpr->evaluateToString(aContext, nsCaseKey);
   NS_ENSURE_SUCCESS(rv, rv);
 
   if (nsCaseKey.IsEmpty()) {
-    aResult = val.forget();
+    aResult = val.release();
 
     return NS_OK;
   }
 
   rv = mCollation->AllocateRawSortKey(nsICollation::kCollationCaseInSensitive,
-                                      nsCaseKey, &val->mKey, &val->mLength);
+                                      nsCaseKey, val->mKey);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  aResult = val.forget();
+  aResult = val.release();
 
   return NS_OK;
 }
@@ -77,17 +80,16 @@ int txResultStringComparator::compareValues(txObject* aVal1, txObject* aVal2) {
 
   if (!mCollation) return -1;
 
-  if (strval1->mLength == 0) {
-    if (strval2->mLength == 0) return 0;
+  if (strval1->mKey.Length() == 0) {
+    if (strval2->mKey.Length() == 0) return 0;
     return ((mSorting & kAscending) ? -1 : 1);
   }
 
-  if (strval2->mLength == 0) return ((mSorting & kAscending) ? 1 : -1);
+  if (strval2->mKey.Length() == 0) return ((mSorting & kAscending) ? 1 : -1);
 
   nsresult rv;
   int32_t result = -1;
-  rv = mCollation->CompareRawSortKey(strval1->mKey, strval1->mLength,
-                                     strval2->mKey, strval2->mLength, &result);
+  rv = mCollation->CompareRawSortKey(strval1->mKey, strval2->mKey, &result);
   if (NS_FAILED(rv)) {
     // XXX ErrorReport
     return -1;
@@ -95,35 +97,22 @@ int txResultStringComparator::compareValues(txObject* aVal1, txObject* aVal2) {
 
   if (result != 0) return ((mSorting & kAscending) ? 1 : -1) * result;
 
-  if ((strval1->mCaseLength == 0) && (strval1->mLength != 0)) {
-    nsString* caseString = (nsString*)strval1->mCaseKey;
-    rv = mCollation->AllocateRawSortKey(
-        nsICollation::kCollationCaseSensitive, *caseString,
-        (uint8_t**)&strval1->mCaseKey, &strval1->mCaseLength);
+  if (strval1->mCaseKeyString && strval1->mKey.Length() != 0) {
+    rv = strval1->initCaseKey(mCollation);
     if (NS_FAILED(rv)) {
       // XXX ErrorReport
-      strval1->mCaseKey = caseString;
-      strval1->mCaseLength = 0;
       return -1;
     }
-    delete caseString;
   }
-  if ((strval2->mCaseLength == 0) && (strval2->mLength != 0)) {
-    nsString* caseString = (nsString*)strval2->mCaseKey;
-    rv = mCollation->AllocateRawSortKey(
-        nsICollation::kCollationCaseSensitive, *caseString,
-        (uint8_t**)&strval2->mCaseKey, &strval2->mCaseLength);
+  if (strval2->mCaseKeyString && strval2->mKey.Length() != 0) {
+    rv = strval2->initCaseKey(mCollation);
     if (NS_FAILED(rv)) {
       // XXX ErrorReport
-      strval2->mCaseKey = caseString;
-      strval2->mCaseLength = 0;
       return -1;
     }
-    delete caseString;
   }
-  rv = mCollation->CompareRawSortKey(
-      (uint8_t*)strval1->mCaseKey, strval1->mCaseLength,
-      (uint8_t*)strval2->mCaseKey, strval2->mCaseLength, &result);
+  rv = mCollation->CompareRawSortKey(strval1->mCaseKey, strval2->mCaseKey,
+                                     &result);
   if (NS_FAILED(rv)) {
     // XXX ErrorReport
     return -1;
@@ -133,15 +122,21 @@ int txResultStringComparator::compareValues(txObject* aVal1, txObject* aVal2) {
          ((mSorting & kUpperFirst) ? -1 : 1) * result;
 }
 
-txResultStringComparator::StringValue::StringValue()
-    : mKey(0), mCaseKey(0), mLength(0), mCaseLength(0) {}
+txResultStringComparator::StringValue::StringValue() = default;
+
+txResultStringComparator::StringValue::~StringValue() = default;
+
+nsresult txResultStringComparator::StringValue::initCaseKey(
+    nsICollation* aCollation) {
+  nsresult rv = aCollation->AllocateRawSortKey(
+      nsICollation::kCollationCaseSensitive, *mCaseKeyString, mCaseKey);
+  if (NS_FAILED(rv)) {
+    mCaseKey.SetLength(0);
+    return rv;
+  }
 
-txResultStringComparator::StringValue::~StringValue() {
-  free(mKey);
-  if (mCaseLength > 0)
-    free(mCaseKey);
-  else
-    delete (nsString*)mCaseKey;
+  mCaseKeyString = nullptr;
+  return NS_OK;
 }
 
 txResultNumberComparator::txResultNumberComparator(bool aAscending) {
@@ -151,7 +146,7 @@ txResultNumberComparator::txResultNumberComparator(bool aAscending) {
 nsresult txResultNumberComparator::createSortableValue(Expr* aExpr,
                                                        txIEvalContext* aContext,
                                                        txObject*& aResult) {
-  nsAutoPtr<NumberValue> numval(new NumberValue);
+  UniquePtr<NumberValue> numval(new NumberValue);
   if (!numval) {
     return NS_ERROR_OUT_OF_MEMORY;
   }
@@ -162,7 +157,7 @@ nsresult txResultNumberComparator::createSortableValue(Expr* aExpr,
 
   numval->mVal = exprRes->numberValue();
 
-  aResult = numval.forget();
+  aResult = numval.release();
 
   return NS_OK;
 }
diff --git a/dom/xslt/xslt/txXPathResultComparator.h b/dom/xslt/xslt/txXPathResultComparator.h
index f4423dac46..0e13e6b241 100644
--- a/dom/xslt/xslt/txXPathResultComparator.h
+++ b/dom/xslt/xslt/txXPathResultComparator.h
@@ -6,6 +6,7 @@
 #define TRANSFRMX_XPATHRESULTCOMPARATOR_H
 
 #include "mozilla/Attributes.h"
+#include "mozilla/UniquePtr.h"
 #include "txCore.h"
 #include "nsCOMPtr.h"
 #include "nsICollation.h"
@@ -58,9 +59,13 @@ class txResultStringComparator : public txXPathResultComparator {
     StringValue();
     ~StringValue();
 
-    uint8_t* mKey;
-    void* mCaseKey;
-    uint32_t mLength, mCaseLength;
+    nsresult initCaseKey(nsICollation* aCollation);
+
+    nsTArray<uint8_t> mKey;
+    // Either mCaseKeyString is non-null, or we have a usable key in mCaseKey
+    // already.
+    mozilla::UniquePtr<nsString> mCaseKeyString;
+    nsTArray<uint8_t> mCaseKey;
   };
 };
 
diff --git a/dom/xslt/xslt/txXSLTFunctions.h b/dom/xslt/xslt/txXSLTFunctions.h
index d789a358c0..160a101b49 100644
--- a/dom/xslt/xslt/txXSLTFunctions.h
+++ b/dom/xslt/xslt/txXSLTFunctions.h
@@ -5,9 +5,9 @@
 #ifndef TRANSFRMX_XSLT_FUNCTIONS_H
 #define TRANSFRMX_XSLT_FUNCTIONS_H
 
+#include "mozilla/UniquePtr.h"
 #include "txExpr.h"
 #include "txXMLUtils.h"
-#include "nsAutoPtr.h"
 #include "txNamespaceMap.h"
 
 class txStylesheet;
diff --git a/dom/xslt/xslt/txXSLTNumber.cpp b/dom/xslt/xslt/txXSLTNumber.cpp
index 3e6196cf94..322b0c96b6 100644
--- a/dom/xslt/xslt/txXSLTNumber.cpp
+++ b/dom/xslt/xslt/txXSLTNumber.cpp
@@ -16,6 +16,9 @@
 
 #include <algorithm>
 
+using mozilla::MakeUnique;
+using mozilla::UniquePtr;
+
 nsresult txXSLTNumber::createNumber(Expr* aValueExpr, txPattern* aCountPattern,
                                     txPattern* aFromPattern, LevelType aLevel,
                                     Expr* aGroupSize, Expr* aGroupSeparator,
@@ -102,7 +105,7 @@ nsresult txXSLTNumber::getValueList(Expr* aValueExpr, txPattern* aCountPattern,
   // Otherwise use count/from/level
 
   txPattern* countPattern = aCountPattern;
-  nsAutoPtr<txPattern> newCountPattern;
+  UniquePtr<txPattern> newCountPattern;
   const txXPathNode& currNode = aContext->getContextNode();
 
   // Parse count- and from-attributes
@@ -146,7 +149,8 @@ nsresult txXSLTNumber::getValueList(Expr* aValueExpr, txPattern* aCountPattern,
       }
     }
     MOZ_ASSERT(nodeTest);
-    countPattern = newCountPattern = new txStepPattern(nodeTest, false);
+    newCountPattern = MakeUnique<txStepPattern>(nodeTest, false);
+    countPattern = newCountPattern.get();
   }
 
   // Generate list of values depending on the value of the level-attribute
@@ -335,12 +339,7 @@ nsresult txXSLTNumber::getCounters(Expr* aGroupSize, Expr* aGroupSeparator,
     NS_ENSURE_SUCCESS(rv, rv);
 
     defaultCounter->mSeparator.Assign('.');
-    rv = aCounters.add(defaultCounter);
-    if (NS_FAILED(rv)) {
-      // XXX ErrorReport: out of memory
-      delete defaultCounter;
-      return rv;
-    }
+    aCounters.add(defaultCounter);
 
     return NS_OK;
   }
@@ -390,16 +389,7 @@ nsresult txXSLTNumber::getCounters(Expr* aGroupSize, Expr* aGroupSeparator,
 
     // Add to list of counters
     counter->mSeparator = sepToken;
-    rv = aCounters.add(counter);
-    if (NS_FAILED(rv)) {
-      // XXX ErrorReport: out of memory
-      txListIterator iter(&aCounters);
-      while (iter.hasNext()) {
-        delete (txFormattedCounter*)iter.next();
-      }
-      aCounters.clear();
-      return rv;
-    }
+    aCounters.add(counter);
   }
 
   return NS_OK;
diff --git a/dom/xslt/xslt/txXSLTPatterns.cpp b/dom/xslt/xslt/txXSLTPatterns.cpp
index 2a0184682f..628a2b1f95 100644
--- a/dom/xslt/xslt/txXSLTPatterns.cpp
+++ b/dom/xslt/xslt/txXSLTPatterns.cpp
@@ -14,6 +14,10 @@
 #include "nsWhitespaceTokenizer.h"
 #include "nsIContent.h"
 
+using mozilla::UniquePtr;
+using mozilla::Unused;
+using mozilla::WrapUnique;
+
 /*
  * Returns the default priority of this Pattern.
  * UnionPatterns don't like this.
@@ -88,7 +92,7 @@ nsresult txLocPathPattern::addStep(txPattern* aPattern, bool isChild) {
   Step* step = mSteps.AppendElement();
   if (!step) return NS_ERROR_OUT_OF_MEMORY;
 
-  step->pattern = aPattern;
+  step->pattern = WrapUnique(aPattern);
   step->isChild = isChild;
 
   return NS_OK;
@@ -200,8 +204,8 @@ txPattern* txLocPathPattern::getSubPatternAt(uint32_t aPos) {
 void txLocPathPattern::setSubPatternAt(uint32_t aPos, txPattern* aPattern) {
   NS_ASSERTION(aPos < mSteps.Length(), "setting bad subexpression index");
   Step* step = &mSteps[aPos];
-  step->pattern.forget();
-  step->pattern = aPattern;
+  Unused << step->pattern.release();
+  step->pattern = WrapUnique(aPattern);
 }
 
 #ifdef TX_TO_STRING
@@ -329,7 +333,7 @@ void txIdPattern::toString(nsAString& aDest) {
 nsresult txKeyPattern::matches(const txXPathNode& aNode,
                                txIMatchContext* aContext, bool& aMatched) {
   txExecutionState* es = (txExecutionState*)aContext->getPrivateContext();
-  nsAutoPtr<txXPathNode> contextDoc(txXPathNodeUtils::getOwnerDocument(aNode));
+  UniquePtr<txXPathNode> contextDoc(txXPathNodeUtils::getOwnerDocument(aNode));
   NS_ENSURE_TRUE(contextDoc, NS_ERROR_FAILURE);
 
   RefPtr<txNodeSet> nodes;
diff --git a/dom/xslt/xslt/txXSLTPatterns.h b/dom/xslt/xslt/txXSLTPatterns.h
index a09b6d438c..efc6c9d18f 100644
--- a/dom/xslt/xslt/txXSLTPatterns.h
+++ b/dom/xslt/xslt/txXSLTPatterns.h
@@ -124,7 +124,7 @@ class txLocPathPattern : public txPattern {
  private:
   class Step {
    public:
-    nsAutoPtr<txPattern> pattern;
+    mozilla::UniquePtr<txPattern> pattern;
     bool isChild;
   };
 
@@ -188,14 +188,14 @@ class txStepPattern : public txPattern, public PredicateList {
   TX_DECL_PATTERN;
   Type getType() override;
 
-  txNodeTest* getNodeTest() { return mNodeTest; }
+  txNodeTest* getNodeTest() { return mNodeTest.get(); }
   void setNodeTest(txNodeTest* aNodeTest) {
-    mNodeTest.forget();
-    mNodeTest = aNodeTest;
+    mozilla::Unused << mNodeTest.release();
+    mNodeTest = mozilla::WrapUnique(aNodeTest);
   }
 
  private:
-  nsAutoPtr<txNodeTest> mNodeTest;
+  mozilla::UniquePtr<txNodeTest> mNodeTest;
   bool mIsAttr;
 };
 
diff --git a/dom/xul/XULDocument.cpp b/dom/xul/XULDocument.cpp
index 544e070ea4..d613defc2e 100644
--- a/dom/xul/XULDocument.cpp
+++ b/dom/xul/XULDocument.cpp
@@ -58,7 +58,6 @@
 #include "nsCharsetSource.h"
 #include "mozilla/StyleSheetInlines.h"
 #include "mozilla/css/Loader.h"
-#include "nsIStyleSheetLinkingElement.h"
 #include "nsXULPopupManager.h"
 #include "nsCCUncollectableMarker.h"
 #include "nsURILoader.h"