Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/fetch/CSSStyleSheetResource.cpp

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller (mueller@kde.org)
     Copyright (C) 2002 Waldo Bastian (bastian@kde.org)
     Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
     Copyright (C) 2004, 2005, 2006 Apple Computer, Inc.
 
     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 133 matching lines @@
     if (hasValidMIMEType)
         *hasValidMIMEType = typeOK;
     if (!enforceMIMEType)
         return true;
     return typeOK;
 }
 
 PassRefPtrWillBeRawPtr<StyleSheetContents> CSSStyleSheetResource::restoreParsedStyleSheet(const CSSParserContext& context)
 {
     if (!m_parsedStyleSheetCache)
-        return 0;
+        return nullptr;
     if (m_parsedStyleSheetCache->hasFailedOrCanceledSubresources()) {
         m_parsedStyleSheetCache->removedFromMemoryCache();
         m_parsedStyleSheetCache.clear();
-        return 0;
+        return nullptr;
     }
 
     ASSERT(m_parsedStyleSheetCache->isCacheable());
     ASSERT(m_parsedStyleSheetCache->isInMemoryCache());
 
     // Contexts must be identical so we know we would get the same exact result if we parsed again.
     if (m_parsedStyleSheetCache->parserContext() != context)
-        return 0;
+        return nullptr;
 
     didAccessDecodedData(currentTime());
 
     return m_parsedStyleSheetCache;
 }
 
 void CSSStyleSheetResource::saveParsedStyleSheet(PassRefPtrWillBeRawPtr<StyleSheetContents> sheet)
 {
     ASSERT(sheet && sheet->isCacheable());
 
     if (m_parsedStyleSheetCache)
         m_parsedStyleSheetCache->removedFromMemoryCache();
     m_parsedStyleSheetCache = sheet;
     m_parsedStyleSheetCache->addedToMemoryCache();
 
     setDecodedSize(m_parsedStyleSheetCache->estimatedSizeInBytes());
 }
 
 }