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

Source/core/rendering/RenderButton.cpp

 /**
  * Copyright (C) 2005 Apple Computer, Inc.
  *
  * 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,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 94 matching lines @@
     // when the content overflows, treat it the same as align-items: flex-start.
     innerStyle->setMarginTop(Length());
     innerStyle->setMarginBottom(Length());
     innerStyle->setFlexDirection(style()->flexDirection());
 }
 
 void RenderButton::updateFromElement()
 {
     // If we're an input element, we may need to change our button text.
     if (node()->hasTagName(inputTag)) {
-        HTMLInputElement* input = static_cast<HTMLInputElement*>(node());
+        Handle<HTMLInputElement> input(static_cast<HTMLInputElement*>(node()));
         String value = input->valueWithDefault();
         setText(value);
     }
 }
 
 void RenderButton::setText(const String& str)
 {
     if (str.isEmpty()) {
         if (m_buttonText) {
             m_buttonText->destroy();
@@ skipping 23 matching lines @@
     return !node()->hasTagName(inputTag);
 }
 
 LayoutRect RenderButton::controlClipRect(const LayoutPoint& additionalOffset) const
 {
     // Clip to the padding box to at least give content the extra padding space.
     return LayoutRect(additionalOffset.x() + borderLeft(), additionalOffset.y() + borderTop(), width() - borderLeft() - borderRight(), height() - borderTop() - borderBottom());
 }
 
 } // namespace WebCore