Improve DEFINE_STATIC_LOCAL()'s handling of Blink GCed objects.

third_party/WebKit/Source/core/dom/custom/CustomElementScheduler.cpp

 /*
  * Copyright (C) 2013 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 33 matching lines @@
 #include "core/html/imports/HTMLImportChild.h"
 #include "core/html/imports/HTMLImportsController.h"
 
 namespace blink {
 
 // FIXME: Consider moving the element's callback queue to ElementRareData.
 typedef HeapHashMap<Member<Element>, Member<CustomElementCallbackQueue>> ElementCallbackQueueMap;
 
 static ElementCallbackQueueMap& callbackQueues()
 {
-    DEFINE_STATIC_LOCAL(Persistent<ElementCallbackQueueMap>, map, (new ElementCallbackQueueMap()));
-    return *map;
+    DEFINE_STATIC_LOCAL(ElementCallbackQueueMap, map, (new ElementCallbackQueueMap));
+    return map;
 }
 
 static CustomElementCallbackQueue& ensureCallbackQueue(RawPtr<Element> element)
 {
     ElementCallbackQueueMap::ValueType* it = callbackQueues().add(element.get(), nullptr).storedValue;
     if (!it->value)
         it->value = CustomElementCallbackQueue::create(element);
     return *it->value.get();
 }
 
@@ skipping 79 matching lines @@
         callbackQueues().clear();
 }
 
 void CustomElementScheduler::microtaskDispatcherDidFinish()
 {
     ASSERT(!CustomElementProcessingStack::inCallbackDeliveryScope());
     callbackQueues().clear();
 }
 
 } // namespace blink