Move the Widget hierarchy to the Oilpan heap.

Source/core/rendering/HitTestResult.h

 /*
  * Copyright (C) 2006 Apple Computer, Inc.
  * Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 128 matching lines @@
     HitTestLocation m_hitTestLocation;
 
     RefPtrWillBeMember<Node> m_innerNode;
     RefPtrWillBeMember<Node> m_innerPossiblyPseudoNode;
     RefPtrWillBeMember<Node> m_innerNonSharedNode;
     // FIXME: Nothing changes this to a value different from m_hitTestLocation!
     LayoutPoint m_pointInInnerNodeFrame; // The hit-tested point in innerNode frame coordinates.
     LayoutPoint m_localPoint; // A point in the local coordinate space of m_innerNonSharedNode's renderer. Allows us to efficiently
                               // determine where inside the renderer we hit on subsequent operations.
     RefPtrWillBeMember<Element> m_innerURLElement;
-    RefPtr<Scrollbar> m_scrollbar;
+    RefPtrWillBeMember<Scrollbar> m_scrollbar;
     bool m_isOverWidget; // Returns true if we are over a widget (and not in the border/padding area of a RenderPart for example).
     bool m_isFirstLetter;
 
     mutable OwnPtrWillBeMember<NodeSet> m_rectBasedTestResult;
 };
 
 } // namespace blink
 
 #endif // HitTestResult_h