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

third_party/WebKit/Source/core/dom/PresentationAttributeStyle.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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 50 matching lines @@
 public:
     DEFINE_INLINE_TRACE() { visitor->trace(value); }
 
     PresentationAttributeCacheKey key;
     Member<StylePropertySet> value;
 };
 
 using PresentationAttributeCache = HeapHashMap<unsigned, Member<PresentationAttributeCacheEntry>, AlreadyHashed>;
 static PresentationAttributeCache& presentationAttributeCache()
 {
-    DEFINE_STATIC_LOCAL(Persistent<PresentationAttributeCache>, cache, (new PresentationAttributeCache()));
-    return *cache;
+    DEFINE_STATIC_LOCAL(PresentationAttributeCache, cache, (new PresentationAttributeCache));
+    return cache;
 }
 
 class PresentationAttributeCacheCleaner {
     WTF_MAKE_NONCOPYABLE(PresentationAttributeCacheCleaner); USING_FAST_MALLOC(PresentationAttributeCacheCleaner);
 public:
     PresentationAttributeCacheCleaner()
         : m_hitCount(0)
         , m_cleanTimer(this, &PresentationAttributeCacheCleaner::cleanCache)
     {
     }
@@ skipping 115 matching lines @@
         presentationAttributeCache().clear();
         presentationAttributeCache().set(cacheHash, newEntry.release());
     } else {
         cacheValue->value = newEntry.release();
     }
 
     return style.release();
 }
 
 } // namespace blink