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

Source/core/rendering/RenderTextControl.cpp

 /**
  * 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 28 matching lines @@
 RenderTextControl::RenderTextControl(Element* element)
     : RenderBlock(element)
 {
     ASSERT(isHTMLTextFormControlElement(element));
 }
 
 RenderTextControl::~RenderTextControl()
 {
 }
 
-HTMLTextFormControlElement* RenderTextControl::textFormControlElement() const
+Result<HTMLTextFormControlElement> RenderTextControl::textFormControlElement() const
 {
     return toHTMLTextFormControlElement(node());
 }
 
 HTMLElement* RenderTextControl::innerTextElement() const
 {
     return textFormControlElement()->innerTextElement();
 }
 
 void RenderTextControl::styleDidChange(StyleDifference diff, const RenderStyle* oldStyle)
@@ skipping 243 matching lines @@
     }
     return placeholderRenderer;
 }
 
 bool RenderTextControl::canBeReplacedWithInlineRunIn() const
 {
     return false;
 }
 
 } // namespace WebCore