[oilpan] Completely move HTMLFormControlElement's hierarchy to the managed heap

Source/core/rendering/RenderTextControl.h

 /*
  * Copyright (C) 2006, 2007 Apple Inc. All rights reserved.
  *           (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/) 
  *
  * 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 15 matching lines @@
 #include "core/rendering/RenderFlexibleBox.h"
 
 namespace WebCore {
 
 class HTMLTextFormControlElement;
 
 class RenderTextControl : public RenderBlock {
 public:
     virtual ~RenderTextControl();
 
-    HTMLTextFormControlElement* textFormControlElement() const;
+    Result<HTMLTextFormControlElement> textFormControlElement() const;
     virtual PassRefPtr<RenderStyle> createInnerTextStyle(const RenderStyle* startStyle) const = 0;
 
 protected:
     RenderTextControl(Element*);
 
     // This convenience function should not be made public because innerTextElement may outlive the render tree.
     HTMLElement* innerTextElement() const;
 
     int scrollbarThickness() const;
     void adjustInnerTextStyle(const RenderStyle* startStyle, RenderStyle* textBlockStyle) const;
@@ skipping 66 matching lines @@
     }
     virtual int firstLineBoxBaseline() const OVERRIDE { return RenderBlock::firstLineBoxBaseline(); }
     virtual int inlineBlockBaseline(LineDirectionMode direction) const OVERRIDE { return RenderBlock::inlineBlockBaseline(direction); }
 
 };
 
 
 } // namespace WebCore
 
 #endif // RenderTextControl_h