Oilpan: Replace RefPtrs to Node and its subclasses in core/xml/ with Oilpan transition types.

Source/core/xml/XPathExpressionNode.h

 /*
  * Copyright (C) 2005 Frerich Raabe <raabe@kde.org>
  * Copyright (C) 2006, 2009 Apple 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 22 matching lines @@
 #include "wtf/Vector.h"
 #include "wtf/text/StringHash.h"
 
 namespace WebCore {
 
     namespace XPath {
 
         struct EvaluationContext {
             WTF_MAKE_FAST_ALLOCATED;
         public:
-            RefPtr<Node> node;
+            RefPtrWillBePersistent<Node> node;
             unsigned long size;
             unsigned long position;
             HashMap<String, String> variableBindings;
 
             bool hadTypeConversionError;
         };
 
         class ParseNode : public NoBaseWillBeGarbageCollectedFinalized<ParseNode> {
         public:
             virtual ~ParseNode() { }
@@ skipping 40 matching lines @@
             bool m_isContextNodeSensitive;
             bool m_isContextPositionSensitive;
             bool m_isContextSizeSensitive;
         };
 
     }
 
 }
 
 #endif // EXPRESSION_H