Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/platform/fonts/FontCache.cpp

 /*
  * Copyright (C) 2006, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Nicholas Shanks <webkit@nickshanks.com>
  *
  * 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 127 matching lines @@
 }
 #endif
 
 static FontDataCache* gFontDataCache = 0;
 
 PassRefPtr<SimpleFontData> FontCache::getFontData(const FontDescription& fontDescription, const AtomicString& family, bool checkingAlternateName, ShouldRetain shouldRetain)
 {
     if (FontPlatformData* platformData = getFontPlatformData(fontDescription, adjustFamilyNameToAvoidUnsupportedFonts(family), checkingAlternateName))
         return fontDataFromFontPlatformData(platformData, shouldRetain);
 
-    return 0;
+    return nullptr;
 }
 
 PassRefPtr<SimpleFontData> FontCache::fontDataFromFontPlatformData(const FontPlatformData* platformData, ShouldRetain shouldRetain)
 {
     if (!gFontDataCache)
         gFontDataCache = new FontDataCache;
 
 #if !ASSERT_DISABLED
     if (shouldRetain == DoNotRetain)
         ASSERT(m_purgePreventCount);
@@ skipping 126 matching lines @@
         clients.append(*it);
 
     ASSERT(numClients == clients.size());
     for (size_t i = 0; i < numClients; ++i)
         clients[i]->fontCacheInvalidated();
 
     purge(ForcePurge);
 }
 
 } // namespace WebCore