Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/wtf/text/WTFString.cpp

 /*
  * (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2010, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2007-2009 Torch Mobile, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 27 matching lines @@
 
 using namespace std;
 
 namespace WTF {
 
 using namespace Unicode;
 using namespace std;
 
 // Construct a string with UTF-16 data.
 String::String(const UChar* characters, unsigned length)
-    : m_impl(characters ? StringImpl::create(characters, length) : 0)
+    : m_impl(characters ? StringImpl::create(characters, length) : nullptr)
 {
 }
 
 // Construct a string with UTF-16 data, from a null-terminated source.
 String::String(const UChar* str)
 {
     if (!str)
         return;
     m_impl = StringImpl::create(str, lengthOfNullTerminatedString(str));
 }
 
 // Construct a string with latin1 data.
 String::String(const LChar* characters, unsigned length)
-    : m_impl(characters ? StringImpl::create(characters, length) : 0)
+    : m_impl(characters ? StringImpl::create(characters, length) : nullptr)
 {
 }
 
 String::String(const char* characters, unsigned length)
-    : m_impl(characters ? StringImpl::create(reinterpret_cast<const LChar*>(characters), length) : 0)
+    : m_impl(characters ? StringImpl::create(reinterpret_cast<const LChar*>(characters), length) : nullptr)
 {
 }
 
 // Construct a string with latin1 data, from a null-terminated source.
 String::String(const LChar* characters)
-    : m_impl(characters ? StringImpl::create(characters) : 0)
+    : m_impl(characters ? StringImpl::create(characters) : nullptr)
 {
 }
 
 String::String(const char* characters)
-    : m_impl(characters ? StringImpl::create(reinterpret_cast<const LChar*>(characters)) : 0)
+    : m_impl(characters ? StringImpl::create(reinterpret_cast<const LChar*>(characters)) : nullptr)
 {
 }
 
 void String::append(const String& string)
 {
     if (string.isEmpty())
         return;
     if (!m_impl) {
         m_impl = string.m_impl;
         return;
@@ skipping 1177 matching lines @@
     buffer.append('\0');
     return buffer;
 }
 
 Vector<char> asciiDebug(String& string)
 {
     return asciiDebug(string.impl());
 }
 
 #endif