Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/loader/HistoryItem.cpp

 /*
  * Copyright (C) 2005, 2006, 2008, 2011 Apple Inc. All rights reserved.
  *
  * 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 203 matching lines @@
 }
 
 void HistoryItem::setFormInfoFromRequest(const ResourceRequest& request)
 {
     if (equalIgnoringCase(request.httpMethod(), "POST")) {
         // FIXME: Eventually we have to make this smart enough to handle the case where
         // we have a stream for the body to handle the "data interspersed with files" feature.
         m_formData = request.httpBody();
         m_formContentType = request.httpContentType();
     } else {
-        m_formData = 0;
+        m_formData = nullptr;
         m_formContentType = nullAtom;
     }
 }
 
 void HistoryItem::setFormData(PassRefPtr<FormData> formData)
 {
     m_formData = formData;
 }
 
 void HistoryItem::setFormContentType(const AtomicString& formContentType)
 {
     m_formContentType = formContentType;
 }
 
 FormData* HistoryItem::formData()
 {
     return m_formData.get();
 }
 
 bool HistoryItem::isCurrentDocument(Document* doc) const
 {
     // FIXME: We should find a better way to check if this is the current document.
     return equalIgnoringFragmentIdentifier(url(), doc->url());
 }
 
 } // namespace WebCore