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

Source/core/html/HTMLTextFormControlElement.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2009, 2010, 2011 Google Inc. All rights reserved.
  *
  * 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
@@ skipping 72 matching lines @@
     bool lastChangeWasUserEdit() const;
     void setInnerTextValue(const String&);
     String innerTextValue() const;
 
     String directionForFormData() const;
 
     void setTextAsOfLastFormControlChangeEvent(const String& text) { m_textAsOfLastFormControlChangeEvent = text; }
 
     virtual void reportMemoryUsage(MemoryObjectInfo*) const OVERRIDE;
 
+    virtual void acceptHeapVisitor(Visitor*) const OVERRIDE;
+
 protected:
     HTMLTextFormControlElement(const QualifiedName&, Document*, HTMLFormElement*);
     bool isPlaceholderEmpty() const;
     virtual void updatePlaceholderText() = 0;
 
     virtual void parseAttribute(const QualifiedName&, const AtomicString&) OVERRIDE;
 
     void cacheSelection(int start, int end, TextFieldSelectionDirection direction)
     {
         m_cachedSelectionStart = start;
@@ skipping 37 matching lines @@
     int m_cachedSelectionStart;
     int m_cachedSelectionEnd;
     TextFieldSelectionDirection m_cachedSelectionDirection;
 };
 
 inline bool isHTMLTextFormControlElement(const Node* node)
 {
     return node->isElementNode() && toElement(node)->isTextFormControl();
 }
 
-inline HTMLTextFormControlElement* toHTMLTextFormControlElement(Node* node)
+inline Result<HTMLTextFormControlElement> toHTMLTextFormControlElement(Node* node)
 {
     ASSERT_WITH_SECURITY_IMPLICATION(!node || isHTMLTextFormControlElement(node));
-    return static_cast<HTMLTextFormControlElement*>(node);
+    return Handle<HTMLTextFormControlElement>(static_cast<HTMLTextFormControlElement*>(node));
 }
 
-HTMLTextFormControlElement* enclosingTextFormControl(const Position&);
+Result<HTMLTextFormControlElement> enclosingTextFormControl(const Position&);
 
 } // namespace
 
 #endif