Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/css/CSSStyleSheet.cpp

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2006, 2007, 2012 Apple Inc. All rights reserved.
  *
  * 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.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 235 matching lines @@
     if (!document)
         return true;
     if (document->securityOrigin()->canRequest(baseURL))
         return true;
     return false;
 }
 
 PassRefPtr<CSSRuleList> CSSStyleSheet::rules()
 {
     if (!canAccessRules())
-        return 0;
+        return nullptr;
     // IE behavior.
     RefPtr<StaticCSSRuleList> nonCharsetRules = StaticCSSRuleList::create();
     unsigned ruleCount = length();
     for (unsigned i = 0; i < ruleCount; ++i) {
         CSSRule* rule = item(i);
         if (rule->type() == CSSRule::CHARSET_RULE)
             continue;
         nonCharsetRules->rules().append(rule);
     }
     return nonCharsetRules.release();
@@ skipping 70 matching lines @@
 
 int CSSStyleSheet::addRule(const String& selector, const String& style, ExceptionState& exceptionState)
 {
     return addRule(selector, style, length(), exceptionState);
 }
 
 
 PassRefPtr<CSSRuleList> CSSStyleSheet::cssRules()
 {
     if (!canAccessRules())
-        return 0;
+        return nullptr;
     if (!m_ruleListCSSOMWrapper)
         m_ruleListCSSOMWrapper = adoptPtr(new StyleSheetCSSRuleList(this));
     return m_ruleListCSSOMWrapper.get();
 }
 
 String CSSStyleSheet::href() const
 {
     return m_contents->originalURL();
 }
 
@@ skipping 42 matching lines @@
     return m_loadCompleted;
 }
 
 void CSSStyleSheet::startLoadingDynamicSheet()
 {
     m_loadCompleted = false;
     m_ownerNode->startLoadingDynamicSheet();
 }
 
 }