Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/html/track/TextTrack.cpp

 /*
  * Copyright (C) 2011 Google Inc.  All rights reserved.
  * Copyright (C) 2011, 2012, 2013 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 79 matching lines @@
 }
 
 const AtomicString& TextTrack::showingKeyword()
 {
     DEFINE_STATIC_LOCAL(const AtomicString, ended, ("showing", AtomicString::ConstructFromLiteral));
     return ended;
 }
 
 TextTrack::TextTrack(Document& document, TextTrackClient* client, const AtomicString& kind, const AtomicString& label, const AtomicString& language, const AtomicString& id, TextTrackType type)
     : TrackBase(TrackBase::TextTrack, label, language, id)
-    , m_cues(0)
-    , m_regions(0)
+    , m_cues(nullptr)
+    , m_regions(nullptr)
     , m_document(&document)
     , m_trackList(0)
     , m_mode(disabledKeyword())
     , m_client(client)
     , m_trackType(type)
     , m_readinessState(NotLoaded)
     , m_trackIndex(invalidTrackIndex)
     , m_renderedTrackIndex(invalidTrackIndex)
     , m_hasBeenConfigured(false)
 {
@@ skipping 83 matching lines @@
 {
     if (!m_cues)
         return;
 
     if (m_client)
         m_client->textTrackRemoveCues(this, m_cues.get());
 
     for (size_t i = 0; i < m_cues->length(); ++i)
         m_cues->item(i)->setTrack(0);
 
-    m_cues = 0;
+    m_cues = nullptr;
 }
 
 TextTrackCueList* TextTrack::activeCues() const
 {
     // 4.8.10.12.5 If the text track mode ... is not the text track disabled mode,
     // then the activeCues attribute must return a live TextTrackCueList object ...
     // ... whose active flag was set when the script started, in text track cue
     // order. Otherwise, it must return null. When an object is returned, the
     // same object must be returned each time.
     // http://www.whatwg.org/specs/web-apps/current-work/#dom-texttrack-activecues
@@ skipping 201 matching lines @@
     return EventTargetNames::TextTrack;
 }
 
 ExecutionContext* TextTrack::executionContext() const
 {
     return m_document;
 }
 
 } // namespace WebCore