Oilpan: move RenderObjects off heap.

Source/core/rendering/RenderObjectChildList.h

 /*
  * Copyright (C) 2009 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 23 matching lines @@
 class RenderObject;
 
 class RenderObjectChildList {
     DISALLOW_ALLOCATION();
 public:
     RenderObjectChildList()
         : m_firstChild(nullptr)
         , m_lastChild(nullptr)
     {
     }
-    void trace(Visitor*);
 
-    RenderObject* firstChild() const { return m_firstChild.get(); }
-    RenderObject* lastChild() const { return m_lastChild.get(); }
+    RenderObject* firstChild() const { return m_firstChild; }
+    RenderObject* lastChild() const { return m_lastChild; }
 
     // FIXME: Temporary while RenderBox still exists. Eventually this will just happen during insert/append/remove methods on the child list, and nobody
     // will need to manipulate firstChild or lastChild directly.
     void setFirstChild(RenderObject* child) { m_firstChild = child; }
     void setLastChild(RenderObject* child) { m_lastChild = child; }
 
     void destroyLeftoverChildren();
 
     RenderObject* removeChildNode(RenderObject* owner, RenderObject*, bool notifyRenderer = true);
     void insertChildNode(RenderObject* owner, RenderObject* newChild, RenderObject* beforeChild, bool notifyRenderer = true);
     void appendChildNode(RenderObject* owner, RenderObject* newChild, bool notifyRenderer = true)
     {
         insertChildNode(owner, newChild, 0, notifyRenderer);
     }
 
 private:
     void invalidatePaintOnRemoval(const RenderObject& oldChild);
 
-    RawPtrWillBeMember<RenderObject> m_firstChild;
-    RawPtrWillBeMember<RenderObject> m_lastChild;
+    RenderObject* m_firstChild;
+    RenderObject* m_lastChild;
 };
 
 } // namespace blink
 
 #endif // RenderObjectChildList_h