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

third_party/WebKit/Source/core/dom/custom/CustomElementObserver.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 22 matching lines @@
 #include "core/dom/Element.h"
 
 namespace blink {
 
 // Maps elements to the observer watching them. At most one per
 // element at a time.
 typedef HeapHashMap<WeakMember<Element>, Member<CustomElementObserver>> ElementObserverMap;
 
 static ElementObserverMap& elementObservers()
 {
-    DEFINE_STATIC_LOCAL(Persistent<ElementObserverMap>, map, (new ElementObserverMap()));
-    return *map;
+    DEFINE_STATIC_LOCAL(ElementObserverMap, map, (new ElementObserverMap));
+    return map;
 }
 
 void CustomElementObserver::notifyElementWasDestroyed(Element* element)
 {
     ElementObserverMap::iterator it = elementObservers().find(element);
     if (it == elementObservers().end())
         return;
     it->value->elementWasDestroyed(element);
 }
 
 void CustomElementObserver::observe(Element* element)
 {
     ElementObserverMap::AddResult result = elementObservers().add(element, this);
     ASSERT_UNUSED(result, result.isNewEntry);
 }
 
 void CustomElementObserver::unobserve(Element* element)
 {
     CustomElementObserver* observer = elementObservers().take(element);
     ASSERT_UNUSED(observer, observer == this);
 }
 
 } // namespace blink