Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/dom/NodeIterator.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2000 Frederik Holljen (frederik.holljen@hig.no)
  * Copyright (C) 2001 Peter Kelly (pmk@post.com)
  * Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2004, 2008 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 72 matching lines @@
 
 NodeIterator::~NodeIterator()
 {
     root()->document().detachNodeIterator(this);
 }
 
 PassRefPtr<Node> NodeIterator::nextNode(ScriptState* state, ExceptionState& exceptionState)
 {
     if (m_detached) {
         exceptionState.throwDOMException(InvalidStateError, "The iterator is detached.");
-        return 0;
+        return nullptr;
     }
 
     RefPtr<Node> result;
 
     m_candidateNode = m_referenceNode;
     while (m_candidateNode.moveToNext(root())) {
         // NodeIterators treat the DOM tree as a flat list of nodes.
         // In other words, FILTER_REJECT does not pass over descendants
         // of the rejected node. Hence, FILTER_REJECT is the same as FILTER_SKIP.
         RefPtr<Node> provisionalResult = m_candidateNode.node;
         bool nodeWasAccepted = acceptNode(state, provisionalResult.get()) == NodeFilter::FILTER_ACCEPT;
         if (state && state->hadException())
             break;
         if (nodeWasAccepted) {
             m_referenceNode = m_candidateNode;
             result = provisionalResult.release();
             break;
         }
     }
 
     m_candidateNode.clear();
     return result.release();
 }
 
 PassRefPtr<Node> NodeIterator::previousNode(ScriptState* state, ExceptionState& exceptionState)
 {
     if (m_detached) {
         exceptionState.throwDOMException(InvalidStateError, "The iterator is detached.");
-        return 0;
+        return nullptr;
     }
 
     RefPtr<Node> result;
 
     m_candidateNode = m_referenceNode;
     while (m_candidateNode.moveToPrevious(root())) {
         // NodeIterators treat the DOM tree as a flat list of nodes.
         // In other words, FILTER_REJECT does not pass over descendants
         // of the rejected node. Hence, FILTER_REJECT is the same as FILTER_SKIP.
         RefPtr<Node> provisionalResult = m_candidateNode.node;
@@ skipping 86 matching lines @@
                     node = NodeTraversal::previous(*node, root());
             }
             if (node)
                 referenceNode.node = node;
         }
     }
 }
 
 
 } // namespace WebCore