Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/web/WebFontImpl.cpp

 /*
  * Copyright (C) 2010 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 36 matching lines @@
 namespace blink {
 
 WebFont* WebFont::create(const WebFontDescription& desc)
 {
     return new WebFontImpl(desc);
 }
 
 WebFontImpl::WebFontImpl(const FontDescription& desc)
     : m_font(desc)
 {
-    m_font.update(0);
+    m_font.update(nullptr);
 }
 
 WebFontDescription WebFontImpl::fontDescription() const
 {
     return WebFontDescription(m_font.fontDescription());
 }
 
 int WebFontImpl::ascent() const
 {
     return m_font.fontMetrics().ascent();
@@ skipping 52 matching lines @@
     return m_font.offsetForPosition(run, position, true);
 }
 
 WebFloatRect WebFontImpl::selectionRectForText(const WebTextRun& run, const WebFloatPoint& leftBaseline, int height, int from, int to) const
 {
     FontCachePurgePreventer fontCachePurgePreventer;
     return m_font.selectionRectForText(run, leftBaseline, height, from, to);
 }
 
 } // namespace blink