Oilpan: have Navigator and its supplements be on the heap by default.

Source/core/frame/Screen.h

 /*
  * Copyright (C) 2007 Apple 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 21 matching lines @@
 
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "core/frame/DOMWindowProperty.h"
 #include "platform/Supplementable.h"
 #include "platform/heap/Handle.h"
 
 namespace blink {
 
 class LocalFrame;
 
-// TODO(Oilpan): when ~DOMWindowProperty is removed, derive from GarbageCollected<> instead.
 class Screen final : public GarbageCollectedFinalized<Screen>, public ScriptWrappable, public DOMWindowProperty, public HeapSupplementable<Screen> {
     DEFINE_WRAPPERTYPEINFO();
     USING_GARBAGE_COLLECTED_MIXIN(Screen);
 public:
     static Screen* create(LocalFrame* frame)
     {
         return new Screen(frame);
     }
 
     unsigned height() const;
     unsigned width() const;
     unsigned colorDepth() const;
     unsigned pixelDepth() const;
     int availLeft() const;
     int availTop() const;
     unsigned availHeight() const;
     unsigned availWidth() const;
 
     DECLARE_VIRTUAL_TRACE();
 
 private:
     explicit Screen(LocalFrame*);
 };
 
 } // namespace blink
 
 #endif // Screen_h