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

Source/core/xml/NativeXPathNSResolver.h

 /*
  * Copyright (C) 2007 Alexey Proskuryakov (ap@nypop.com)
  *
  * 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.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 17 matching lines @@
 
 #include "core/xml/XPathNSResolver.h"
 #include "wtf/RefPtr.h"
 
 namespace blink {
 
 class Node;
 
 class NativeXPathNSResolver final : public XPathNSResolver {
 public:
-    static PassRefPtrWillBeRawPtr<NativeXPathNSResolver> create(PassRefPtrWillBeRawPtr<Node> node)
+    static NativeXPathNSResolver* create(PassRefPtrWillBeRawPtr<Node> node)
     {
-        return adoptRefWillBeNoop(new NativeXPathNSResolver(node));
+        return new NativeXPathNSResolver(node);
     }
 
     virtual AtomicString lookupNamespaceURI(const String& prefix) override;
 
     DECLARE_VIRTUAL_TRACE();
 
 private:
     explicit NativeXPathNSResolver(PassRefPtrWillBeRawPtr<Node>);
 
     RefPtrWillBeMember<Node> m_node;
 };
 
 } // namespace blink
 
 #endif // NativeXPathNSResolver_h