Oilpan: have WebPerformance use transition types.

Source/core/frame/DOMWindow.h

 /*
  * Copyright (C) 2006, 2007, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  *
  * 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 345 matching lines @@
         mutable RefPtr<Location> m_location;
         mutable RefPtr<StyleMedia> m_media;
 
         String m_status;
         String m_defaultStatus;
 
         mutable RefPtrWillBePersistent<Storage> m_sessionStorage;
         mutable RefPtrWillBePersistent<Storage> m_localStorage;
         mutable RefPtr<ApplicationCache> m_applicationCache;
 
-        mutable RefPtr<Performance> m_performance;
+        mutable RefPtrWillBePersistent<Performance> m_performance;
 
         mutable RefPtr<DOMWindowCSS> m_css;
 
         RefPtr<DOMWindowEventQueue> m_eventQueue;
         RefPtr<SerializedScriptValue> m_pendingStateObject;
     };
 
     inline String DOMWindow::status() const
     {
         return m_status;
     }
 
     inline String DOMWindow::defaultStatus() const
     {
         return m_defaultStatus;
     }
 
 } // namespace WebCore
 
 #endif // DOMWindow_h