Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/html/ImageData.cpp

 /*
  * Copyright (C) 2008 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 19 matching lines @@
 #include "core/html/ImageData.h"
 
 namespace WebCore {
 
 PassRefPtr<ImageData> ImageData::create(const IntSize& size)
 {
     Checked<int, RecordOverflow> dataSize = 4;
     dataSize *= size.width();
     dataSize *= size.height();
     if (dataSize.hasOverflowed())
-        return 0;
+        return nullptr;
 
     return adoptRef(new ImageData(size));
 }
 
 PassRefPtr<ImageData> ImageData::create(const IntSize& size, PassRefPtr<Uint8ClampedArray> byteArray)
 {
     Checked<int, RecordOverflow> dataSize = 4;
     dataSize *= size.width();
     dataSize *= size.height();
     if (dataSize.hasOverflowed())
-        return 0;
+        return nullptr;
 
     if (dataSize.unsafeGet() < 0
         || static_cast<unsigned>(dataSize.unsafeGet()) > byteArray->length())
-        return 0;
+        return nullptr;
 
     return adoptRef(new ImageData(size, byteArray));
 }
 
 ImageData::ImageData(const IntSize& size)
     : m_size(size)
     , m_data(Uint8ClampedArray::createUninitialized(size.width() * size.height() * 4))
 {
     ScriptWrappable::init(this);
 }
 
 ImageData::ImageData(const IntSize& size, PassRefPtr<Uint8ClampedArray> byteArray)
     : m_size(size)
     , m_data(byteArray)
 {
     ASSERT_WITH_SECURITY_IMPLICATION(static_cast<unsigned>(size.width() * size.height() * 4) <= m_data->length());
     ScriptWrappable::init(this);
 }
 
 }