Oilpan: have xml/ objects on the heap by default.

Source/core/xml/XMLSerializer.h

 /*
  *  Copyright (C) 2003, 2006 Apple Computer, Inc.
  *  Copyright (C) 2006 Samuel Weinig (sam@webkit.org)
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Lesser General Public
  *  License as published by the Free Software Foundation; either
  *  version 2 of the License, or (at your option) any later version.
  *
  *  This library is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  *  Lesser General Public License for more details.
  *
  *  You should have received a copy of the GNU Lesser General Public
  *  License along with this library; if not, write to the Free Software
  *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
 #ifndef XMLSerializer_h
 #define XMLSerializer_h
 
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "platform/heap/Handle.h"
-#include "wtf/Forward.h"
-#include "wtf/PassRefPtr.h"
-#include "wtf/RefCounted.h"
 
 namespace blink {
 
 class Node;
 
-class XMLSerializer final : public RefCountedWillBeGarbageCollected<XMLSerializer>, public ScriptWrappable {
+class XMLSerializer final : public GarbageCollected<XMLSerializer>, public ScriptWrappable {
     DEFINE_WRAPPERTYPEINFO();
 public:
-    static PassRefPtrWillBeRawPtr<XMLSerializer> create()
+    static XMLSerializer* create()
     {
-        return adoptRefWillBeNoop(new XMLSerializer);
+        return new XMLSerializer;
     }
 
     String serializeToString(Node*);
 
     DEFINE_INLINE_TRACE() { }
 
 private:
     XMLSerializer() { }
 };
 
 } // namespace blink
 
 #endif // XMLSerializer_h