[@container] style() query unset on root element crashes

Discovered when trying to fix issue 376834363. StyleResolver::ComputeValue() does not set up a parent style for the root element which meant applying unset would crash. There was already a check for inherit. Do the same for unset. Bug: 376834363 Change-Id: I075dd462668436f98a6f7924929f5baba6eeba09 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5999996 Commit-Queue: Rune Lillesveen <[email protected]> Reviewed-by: Anders Hartvoll Ruud <[email protected]> Cr-Commit-Position: refs/heads/main@{#1379181}
web-platform-tests · Nov 6, 2024 · 92228c4 · 92228c4
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commit 92228c4
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diff --git a/css/css-conditional/container-queries/style-query-unset-on-root.html b/css/css-conditional/container-queries/style-query-unset-on-root.html
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+<!DOCTYPE html>
+<title>CSS Container Queries Test: query unset style for custom property on :root should always match</title>
+<link rel="help" href="https://drafts.csswg.org/css-conditional-5/#style-container">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="support/cq-testcommon.js"></script>
+<style>
+  :root { container-name: --root; }
+  @container --root style(--foo: unset) {
+    #target { color: green; }
+  }
+</style>
+<div id="target"></div>
+<script>
+  setup(() => assert_implements_style_container_queries());
+
+  test(() => {
+    assert_equals(getComputedStyle(target).color, "rgb(0, 128, 0)");
+  }, "Match style(--foo: unset) on :root element");
+</script>