Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/html/canvas/CanvasStyle.cpp

 /*
  * Copyright (C) 2006, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2008 Eric Seidel <eric@webkit.org>
  *
  * 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
@@ skipping 116 matching lines @@
 {
     RGBA32 rgba;
     ColorParseResult parseResult = parseColor(rgba, color, document);
     switch (parseResult) {
     case ParsedRGBA:
     case ParsedSystemColor:
         return adoptRef(new CanvasStyle(rgba));
     case ParsedCurrentColor:
         return adoptRef(new CanvasStyle(CurrentColor));
     case ParseFailed:
-        return 0;
+        return nullptr;
     default:
         ASSERT_NOT_REACHED();
-        return 0;
+        return nullptr;
     }
 }
 
 PassRefPtr<CanvasStyle> CanvasStyle::createFromStringWithOverrideAlpha(const String& color, float alpha)
 {
     RGBA32 rgba;
     ColorParseResult parseResult = parseColor(rgba, color);
     switch (parseResult) {
     case ParsedRGBA:
         return adoptRef(new CanvasStyle(colorWithOverrideAlpha(rgba, alpha)));
     case ParsedCurrentColor:
         return adoptRef(new CanvasStyle(CurrentColorWithOverrideAlpha, alpha));
     case ParseFailed:
-        return 0;
+        return nullptr;
     default:
         ASSERT_NOT_REACHED();
-        return 0;
+        return nullptr;
     }
 }
 
 PassRefPtr<CanvasStyle> CanvasStyle::createFromGradient(PassRefPtr<CanvasGradient> gradient)
 {
     if (!gradient)
-        return 0;
+        return nullptr;
     return adoptRef(new CanvasStyle(gradient));
 }
+
 PassRefPtr<CanvasStyle> CanvasStyle::createFromPattern(PassRefPtr<CanvasPattern> pattern)
 {
     if (!pattern)
-        return 0;
+        return nullptr;
     return adoptRef(new CanvasStyle(pattern));
 }
 
 bool CanvasStyle::isEquivalentColor(const CanvasStyle& other) const
 {
     if (m_type != other.m_type)
         return false;
 
     switch (m_type) {
     case RGBA:
@@ skipping 83 matching lines @@
         context->setFillPattern(canvasPattern()->pattern());
         break;
     case CurrentColor:
     case CurrentColorWithOverrideAlpha:
         ASSERT_NOT_REACHED();
         break;
     }
 }
 
 }