Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/xml/XPathEvaluator.cpp

 /*
  * 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 38 matching lines @@
 PassRefPtrWillBeRawPtr<XPathNSResolver> XPathEvaluator::createNSResolver(Node* nodeResolver)
 {
     return NativeXPathNSResolver::create(nodeResolver);
 }
 
 PassRefPtrWillBeRawPtr<XPathResult> XPathEvaluator::evaluate(const String& expression, Node* contextNode,
     PassRefPtrWillBeRawPtr<XPathNSResolver> resolver, unsigned short type, XPathResult* result, ExceptionState& exceptionState)
 {
     if (!contextNode) {
         exceptionState.throwDOMException(NotSupportedError, "The context node provided is null.");
-        return 0;
+        return nullptr;
     }
 
     if (!isValidContextNode(contextNode)) {
         exceptionState.throwDOMException(NotSupportedError, "The node provided is '" + contextNode->nodeName() + "', which is not a valid context node type.");
-        return 0;
+        return nullptr;
     }
 
     RefPtrWillBeRawPtr<XPathExpression> expr = createExpression(expression, resolver, exceptionState);
     if (exceptionState.hadException())
-        return 0;
+        return nullptr;
 
     return expr->evaluate(contextNode, type, result, exceptionState);
 }
 
 }