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

Source/core/html/HTMLTextFormControlElement.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 Apple Inc. All rights reserved.
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.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
@@ skipping 622 matching lines @@
                 getNextSoftBreak(line, breakNode, breakOffset);
             }
             result.append(data.characters() + position, length - position);
         }
         while (breakNode == node)
             getNextSoftBreak(line, breakNode, breakOffset);
     }
     return finishText(result);
 }
 
-HTMLTextFormControlElement* enclosingTextFormControl(const Position& position)
+Result<HTMLTextFormControlElement> enclosingTextFormControl(const Position& position)
 {
     ASSERT(position.isNull() || position.anchorType() == Position::PositionIsOffsetInAnchor
         || position.containerNode() || !position.anchorNode()->shadowHost()
         || (position.anchorNode()->parentNode() && position.anchorNode()->parentNode()->isShadowRoot()));
         
     Node* container = position.containerNode();
     if (!container)
-        return 0;
+        return nullptr;
     Element* ancestor = container->shadowHost();
-    return ancestor && isHTMLTextFormControlElement(ancestor) ? toHTMLTextFormControlElement(ancestor) : 0;
+    return ancestor && isHTMLTextFormControlElement(ancestor) ? toHTMLTextFormControlElement(ancestor) : nullptr;
 }
 
 static const Element* parentHTMLElement(const Element* element)
 {
     while (element) {
         element = element->parentElement();
         if (element && element->isHTMLElement())
             return element;
     }
     return 0;
@@ skipping 19 matching lines @@
     return "ltr";
 }
 
 void HTMLTextFormControlElement::reportMemoryUsage(MemoryObjectInfo* memoryObjectInfo) const
 {
     MemoryClassInfo info(memoryObjectInfo, this, WebCoreMemoryTypes::DOM);
     HTMLFormControlElementWithState::reportMemoryUsage(memoryObjectInfo);
     info.addMember(m_textAsOfLastFormControlChangeEvent, "textAsOfLastFormControlChangeEvent");
 }
 
+void HTMLTextFormControlElement::acceptHeapVisitor(Visitor* visitor) const
+{
+    HTMLFormControlElementWithState::acceptHeapVisitor(visitor);
+}
+
 } // namespace Webcore