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

Source/core/xml/XPathExpression.h

 /*
  * Copyright 2005 Frerich Raabe <raabe@kde.org>
  * Copyright (C) 2006 Apple Computer, Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 12 matching lines @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef XPathExpression_h
 #define XPathExpression_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 ExceptionState;
 class Node;
 class ScriptValue;
 class XPathNSResolver;
 class XPathResult;
 
 namespace XPath {
 class Expression;
 }
 
-class XPathExpression : public RefCountedWillBeGarbageCollected<XPathExpression>, public ScriptWrappable {
-    DECLARE_EMPTY_DESTRUCTOR_WILL_BE_REMOVED(XPathExpression);
+class XPathExpression : public GarbageCollected<XPathExpression>, public ScriptWrappable {
     DEFINE_WRAPPERTYPEINFO();
 public:
-    static PassRefPtrWillBeRawPtr<XPathExpression> create()
+    static XPathExpression* create()
     {
-        return adoptRefWillBeNoop(new XPathExpression);
+        return new XPathExpression;
     }
 
-    static PassRefPtrWillBeRawPtr<XPathExpression> createExpression(const String& expression, PassRefPtrWillBeRawPtr<XPathNSResolver>, ExceptionState&);
-    PassRefPtrWillBeRawPtr<XPathResult> evaluate(Node* contextNode, unsigned short type, const ScriptValue&, ExceptionState&);
+    static XPathExpression* createExpression(const String& expression, XPathNSResolver*, ExceptionState&);
+    XPathResult* evaluate(Node* contextNode, unsigned short type, const ScriptValue&, ExceptionState&);
 
     DECLARE_TRACE();
 
 private:
     XPathExpression();
 
-    OwnPtrWillBeMember<XPath::Expression> m_topExpression;
+    Member<XPath::Expression> m_topExpression;
 };
 
 } // namespace blink
 
 #endif // XPathExpression_h