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

Source/core/rendering/RenderTextControlSingleLine.h

 /*
  * Copyright (C) 2006, 2007, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
  *
  * 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 27 matching lines @@
     virtual PassRefPtr<RenderStyle> createInnerTextStyle(const RenderStyle* startStyle) const;
     PassRefPtr<RenderStyle> createInnerBlockStyle(const RenderStyle* startStyle) const;
 
     void capsLockStateMayHaveChanged();
 
 protected:
     virtual void centerContainerIfNeeded(RenderBox*) const { }
     virtual LayoutUnit computeLogicalHeightLimit() const;
     HTMLElement* containerElement() const;
     HTMLElement* innerBlockElement() const;
-    HTMLInputElement* inputElement() const;
+    Result<HTMLInputElement> inputElement() const;
     virtual void updateFromElement() OVERRIDE;
 
 private:
     virtual bool hasControlClip() const;
     virtual LayoutRect controlClipRect(const LayoutPoint&) const;
     virtual bool isTextField() const { return true; }
 
     virtual void paint(PaintInfo&, const LayoutPoint&);
     virtual void layout();
 
@@ skipping 53 matching lines @@
 public:
     RenderTextControlInnerBlock(Element* element) : RenderBlock(element) { }
 
 private:
     virtual bool hasLineIfEmpty() const { return true; }
 };
 
 }
 
 #endif