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

Source/core/html/HTMLButtonElement.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, 2010 Apple Inc. All rights reserved.
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2007 Samuel Weinig (sam@webkit.org)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 31 matching lines @@
 
 inline HTMLButtonElement::HTMLButtonElement(const QualifiedName& tagName, Document* document, HTMLFormElement* form)
     : HTMLFormControlElement(tagName, document, form)
     , m_type(SUBMIT)
     , m_isActivatedSubmit(false)
 {
     ASSERT(hasTagName(buttonTag));
     ScriptWrappable::init(this);
 }
 
-PassRefPtr<HTMLButtonElement> HTMLButtonElement::create(const QualifiedName& tagName, Document* document, HTMLFormElement* form)
+Result<HTMLButtonElement> HTMLButtonElement::create(const QualifiedName& tagName, Document* document, HTMLFormElement* form)
 {
-    return adoptRef(new HTMLButtonElement(tagName, document, form));
+    return adoptNode(new HTMLButtonElement(tagName, document, form));
 }
 
 void HTMLButtonElement::setType(const AtomicString& type)
 {
     setAttribute(typeAttr, type);
 }
 
 RenderObject* HTMLButtonElement::createRenderer(RenderArena* arena, RenderStyle*)
 {
     return new (arena) RenderButton(this);
@@ skipping 136 matching lines @@
 String HTMLButtonElement::value() const
 {
     return getAttribute(valueAttr);
 }
 
 bool HTMLButtonElement::recalcWillValidate() const
 {
     return m_type == SUBMIT && HTMLFormControlElement::recalcWillValidate();
 }
 
+void HTMLButtonElement::acceptHeapVisitor(Visitor* visitor) const
+{
+    HTMLFormControlElement::acceptHeapVisitor(visitor);
+}
+
 } // namespace