Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/platform/fonts/harfbuzz/HarfBuzzFace.cpp

 /*
  * Copyright (c) 2012 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 64 matching lines @@
 {
     DEFINE_STATIC_LOCAL(HarfBuzzFaceCache, s_harfBuzzFaceCache, ());
     return &s_harfBuzzFaceCache;
 }
 
 HarfBuzzFace::HarfBuzzFace(FontPlatformData* platformData, uint64_t uniqueID)
     : m_platformData(platformData)
     , m_uniqueID(uniqueID)
     , m_scriptForVerticalText(HB_SCRIPT_INVALID)
 {
-    HarfBuzzFaceCache::AddResult result = harfBuzzFaceCache()->add(m_uniqueID, 0);
+    HarfBuzzFaceCache::AddResult result = harfBuzzFaceCache()->add(m_uniqueID, nullptr);
     if (result.isNewEntry)
         result.storedValue->value = FaceCacheEntry::create(createFace());
     result.storedValue->value->ref();
     m_face = result.storedValue->value->face();
     m_glyphCacheForFaceCacheEntry = result.storedValue->value->glyphCache();
 }
 
 HarfBuzzFace::~HarfBuzzFace()
 {
     HarfBuzzFaceCache::iterator result = harfBuzzFaceCache()->find(m_uniqueID);
@@ skipping 26 matching lines @@
 }
 
 void HarfBuzzFace::setScriptForVerticalGlyphSubstitution(hb_buffer_t* buffer)
 {
     if (m_scriptForVerticalText == HB_SCRIPT_INVALID)
         m_scriptForVerticalText = findScriptForVerticalGlyphSubstitution(m_face);
     hb_buffer_set_script(buffer, m_scriptForVerticalText);
 }
 
 } // namespace WebCore