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

Source/core/dom/Node.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2009 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
@@ skipping 468 matching lines @@
         delete static_cast<NodeRareData*>(m_data.m_rareData);
     m_data.m_renderer = renderer;
     clearFlag(HasRareDataFlag);
 }
 
 Node* Node::toNode()
 {
     return this;
 }
 
-HTMLInputElement* Node::toInputElement()
+Result<HTMLInputElement> Node::toInputElement()
 {
     // If one of the below ASSERTs trigger, you are calling this function
     // directly or indirectly from a constructor or destructor of this object.
     // Don't do this!
     ASSERT(!(isHTMLElement() && hasTagName(inputTag)));
-    return 0;
+    return nullptr;
 }
 
 short Node::tabIndex() const
 {
     return 0;
 }
 
 String Node::nodeValue() const
 {
     return String();
@@ skipping 2234 matching lines @@
         node->showTreeForThis();
 }
 
 void showNodePath(const WebCore::Node* node)
 {
     if (node)
         node->showNodePathForThis();
 }
 
 #endif