Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/css/CSSDefaultStyleSheets.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
@@ skipping 68 matching lines @@
     return parseUASheet(String(characters, size));
 }
 
 CSSDefaultStyleSheets::CSSDefaultStyleSheets()
     : m_defaultStyle(0)
     , m_defaultViewportStyle(0)
     , m_defaultQuirksStyle(0)
     , m_defaultPrintStyle(0)
     , m_defaultViewSourceStyle(0)
     , m_defaultXHTMLMobileProfileStyle(0)
-    , m_defaultStyleSheet(0)
-    , m_viewportStyleSheet(0)
-    , m_quirksStyleSheet(0)
-    , m_svgStyleSheet(0)
-    , m_mediaControlsStyleSheet(0)
-    , m_fullscreenStyleSheet(0)
+    , m_defaultStyleSheet(nullptr)
+    , m_viewportStyleSheet(nullptr)
+    , m_quirksStyleSheet(nullptr)
+    , m_svgStyleSheet(nullptr)
+    , m_mediaControlsStyleSheet(nullptr)
+    , m_fullscreenStyleSheet(nullptr)
 {
     m_defaultStyle = RuleSet::create().leakPtr();
     m_defaultViewportStyle = RuleSet::create().leakPtr();
     m_defaultPrintStyle = RuleSet::create().leakPtr();
     m_defaultQuirksStyle = RuleSet::create().leakPtr();
 
     // Strict-mode rules.
     String defaultRules = String(htmlUserAgentStyleSheet, sizeof(htmlUserAgentStyleSheet)) + RenderTheme::theme().extraDefaultStyleSheet();
     m_defaultStyleSheet = parseUASheet(defaultRules);
     m_defaultStyle->addRulesFromSheet(defaultStyleSheet(), screenEval());
@@ skipping 71 matching lines @@
 {
     visitor->trace(m_defaultStyleSheet);
     visitor->trace(m_viewportStyleSheet);
     visitor->trace(m_quirksStyleSheet);
     visitor->trace(m_svgStyleSheet);
     visitor->trace(m_mediaControlsStyleSheet);
     visitor->trace(m_fullscreenStyleSheet);
 }
 
 } // namespace WebCore