Replace RenderArena with PartitionAlloc.

Source/core/rendering/RenderWidget.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2005, 2006, 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.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 49 matching lines @@
 
     Widget* widget() const { return m_widget.get(); }
     virtual void setWidget(PassRefPtr<Widget>);
 
     static RenderWidget* find(const Widget*);
 
     void updateWidgetPosition();
     void widgetPositionsUpdated();
     IntRect windowClipRect() const;
 
-    RenderArena* ref() { ++m_refCount; return renderArena(); }
-    void deref(RenderArena*);
+    void ref() { ++m_refCount; }
+    void deref();
 
 protected:
     RenderWidget(Element*);
 
     FrameView* frameView() const { return m_frameView; }
 
     void clearWidget();
 
     virtual void styleDidChange(StyleDifference, const RenderStyle* oldStyle) OVERRIDE FINAL;
     virtual void layout();
@@ skipping 30 matching lines @@
     ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isWidget());
     return static_cast<const RenderWidget*>(object);
 }
 
 // This will catch anyone doing an unnecessary cast.
 void toRenderWidget(const RenderWidget*);
 
 } // namespace WebCore
 
 #endif // RenderWidget_h