Oilpan: move RenderObjects off heap.

Source/core/rendering/RenderBlock.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  *
  * 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.
@@ skipping 37 matching lines @@
 typedef Vector<WordMeasurement, 64> WordMeasurements;
 
 enum ContainingBlockState { NewContainingBlock, SameContainingBlock };
 
 typedef WTF::HashMap<RenderBlock*, OwnPtr<ListHashSet<RenderInline*> > > ContinuationOutlineTableMap;
 
 ContinuationOutlineTableMap* continuationOutlineTable();
 
 class RenderBlock : public RenderBox {
 public:
-    virtual void destroy() override;
-    virtual void trace(Visitor*) override;
     friend class LineLayoutState;
 
 protected:
     explicit RenderBlock(ContainerNode*);
     virtual ~RenderBlock();
 
 public:
     RenderObject* firstChild() const { ASSERT(children() == virtualChildren()); return children()->firstChild(); }
     RenderObject* lastChild() const { ASSERT(children() == virtualChildren()); return children()->lastChild(); }
 
@@ skipping 405 matching lines @@
     // FIXME: This is temporary as we move code that accesses block flow
     // member variables out of RenderBlock and into RenderBlockFlow.
     friend class RenderBlockFlow;
 };
 
 DEFINE_RENDER_OBJECT_TYPE_CASTS(RenderBlock, isRenderBlock());
 
 } // namespace blink
 
 #endif // RenderBlock_h