Oilpan: have Storage objects reside on the heap by default.

Source/modules/storage/StorageArea.h

 /*
  * Copyright (C) 2009 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 30 matching lines @@
 class SecurityOrigin;
 class Storage;
 class WebStorageArea;
 class WebStorageNamespace;
 
 enum StorageType {
     LocalStorage,
     SessionStorage
 };
 
-class MODULES_EXPORT StorageArea final : public NoBaseWillBeGarbageCollectedFinalized<StorageArea>, public LocalFrameLifecycleObserver {
+class MODULES_EXPORT StorageArea final : public GarbageCollectedFinalized<StorageArea>, public LocalFrameLifecycleObserver {
     WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(StorageArea);
 public:
-    static PassOwnPtrWillBeRawPtr<StorageArea> create(PassOwnPtr<WebStorageArea>, StorageType);
+    static StorageArea* create(PassOwnPtr<WebStorageArea>, StorageType);
 
     virtual ~StorageArea();
 
     // The HTML5 DOM Storage API
     unsigned length(ExceptionState&, LocalFrame* sourceFrame);
     String key(unsigned index, ExceptionState&, LocalFrame* sourceFrame);
     String getItem(const String& key, ExceptionState&, LocalFrame* sourceFrame);
     void setItem(const String& key, const String& value, ExceptionState&, LocalFrame* sourceFrame);
     void removeItem(const String& key, ExceptionState&, LocalFrame* sourceFrame);
     void clear(ExceptionState&, LocalFrame* sourceFrame);
@@ skipping 16 matching lines @@
     static bool isEventSource(Storage*, WebStorageArea* sourceAreaInstance);
 
     OwnPtr<WebStorageArea> m_storageArea;
     StorageType m_storageType;
     bool m_canAccessStorageCachedResult;
 };
 
 } // namespace blink
 
 #endif // StorageArea_h