Oilpan: move RenderObjects off heap.

Source/core/layout/LayoutTableCol.h

 /*
  * Copyright (C) 1997 Martin Jones (mjones@kde.org)
  *           (C) 1997 Torben Weis (weis@kde.org)
  *           (C) 1998 Waldo Bastian (bastian@kde.org)
  *           (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 18 matching lines @@
 #include "core/rendering/RenderBox.h"
 
 namespace blink {
 
 class LayoutTable;
 class LayoutTableCell;
 
 class LayoutTableCol final : public RenderBox {
 public:
     explicit LayoutTableCol(Element*);
-    virtual void trace(Visitor*) override;
 
     RenderObject* firstChild() const { ASSERT(children() == virtualChildren()); return children()->firstChild(); }
 
     // If you have a LayoutTableCol, use firstChild or lastChild instead.
     void slowFirstChild() const = delete;
     void slowLastChild() const = delete;
 
     const RenderObjectChildList* children() const { return &m_children; }
     RenderObjectChildList* children() { return &m_children; }
 
@@ skipping 54 matching lines @@
 
     RenderObjectChildList m_children;
     unsigned m_span;
 };
 
 DEFINE_RENDER_OBJECT_TYPE_CASTS(LayoutTableCol, isLayoutTableCol());
 
 }
 
 #endif