Oilpan: move DOM string collection objects to the Oilpan heap.

Source/core/html/HTMLElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2011 Motorola Mobility. 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 932 matching lines @@
     // even in spatial navigation mode instead of handling it as a "click" action.
     if (isTextFormControl() || isContentEditable())
         return;
     int charCode = event->charCode();
     if (charCode == '\r' || charCode == ' ') {
         dispatchSimulatedClick(event);
         event->setDefaultHandled();
     }
 }
 
+void HTMLElement::trace(Visitor* visitor)
+{
+    Element::trace(visitor);
+}
+
 } // namespace WebCore
 
 #ifndef NDEBUG
 
 // For use in the debugger
 void dumpInnerHTML(WebCore::HTMLElement*);
 
 void dumpInnerHTML(WebCore::HTMLElement* element)
 {
     printf("%s\n", element->innerHTML().ascii().data());
 }
 #endif