Pust push behind context-param com.sun.faces.enablePushResources, dis…

…abled by default.

modified:   jsf-ri/src/main/java/com/sun/faces/application/ApplicationAssociate.java

- Modify checkForPushBuilder() to return false unless
  EnablePushResources is true.

modified:   jsf-ri/src/main/java/com/sun/faces/config/WebConfiguration.java

- Declare new BooleanWebContextParam

jsf-ri/src/main/java/com/sun/faces/application/ApplicationAssociate.java

@@ -284,6 +284,11 @@ public ApplicationAssociate(ApplicationImpl appImpl) {
 
     private boolean checkForPushBuilder() {
         boolean result = false;
+
+        if (!webConfig.isOptionEnabled(BooleanWebContextInitParameter.EnablePushResources)) {
+            return result;
+        }
+
         Class clazz = HttpServletRequest.class;
         try {
             result = null != clazz.getMethod("newPushBuilder", (Class[]) null);

jsf-ri/src/main/java/com/sun/faces/config/WebConfiguration.java

@@ -1242,6 +1242,10 @@ public enum BooleanWebContextInitParameter {
               "com.sun.faces.enableCoreTagLibValidator",
               false
         ),
+        EnablePushResources(
+              "com.sun.faces.enablePushResources",
+              false
+        ),
         PreferXHTMLContentType(
               "com.sun.faces.preferXHTML",
               false