Run Mutation Observer and Custom Element callbacks consistently at microtask checkpoint

Source/core/dom/CustomElementRegistry.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 307 matching lines @@
 {
     while (!activeCustomElementRegistries().isEmpty()) {
         Vector<RefPtr<CustomElementRegistry> > registries;
         copyToVector(activeCustomElementRegistries(), registries);
         activeCustomElementRegistries().clear();
         for (size_t i = 0; i < registries.size(); ++i)
             registries[i]->deliverLifecycleCallbacks();
     }
 }
 
+bool CustomElementRegistry::hasQueuedLifecycleCallbacks()
+{
+    return !activeCustomElementRegistries().isEmpty();
 }
+
+void CustomElementRegistry::abandonAllQueuedLifecycleCallbacks()
+{
+    for (InstanceSet::iterator it = activeCustomElementRegistries().begin(); it != activeCustomElementRegistries().end(); ++it)
+        (*it)->abandonQueuedLifecycleCallbacks();
+    activeCustomElementRegistries().clear();
+}
+
+void CustomElementRegistry::abandonQueuedLifecycleCallbacks()
+{
+    m_invocations.clear();
+}
+
+}