Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/css/Rect.h

 /*
  * Copyright (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 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 37 matching lines @@
             && compareCSSValuePtr(m_bottom, other.m_bottom);
     }
 
     void trace(Visitor*);
 
     ~RectBase() { }
 
 protected:
     RectBase() { }
     RectBase(const RectBase& cloneFrom)
-        : m_top(cloneFrom.m_top ? cloneFrom.m_top->cloneForCSSOM() : 0)
-        , m_right(cloneFrom.m_right ? cloneFrom.m_right->cloneForCSSOM() : 0)
-        , m_bottom(cloneFrom.m_bottom ? cloneFrom.m_bottom->cloneForCSSOM() : 0)
-        , m_left(cloneFrom.m_left ? cloneFrom.m_left->cloneForCSSOM() : 0)
+        : m_top(cloneFrom.m_top ? cloneFrom.m_top->cloneForCSSOM() : nullptr)
+        , m_right(cloneFrom.m_right ? cloneFrom.m_right->cloneForCSSOM() : nullptr)
+        , m_bottom(cloneFrom.m_bottom ? cloneFrom.m_bottom->cloneForCSSOM() : nullptr)
+        , m_left(cloneFrom.m_left ? cloneFrom.m_left->cloneForCSSOM() : nullptr)
     {
     }
 
 private:
     RefPtrWillBeMember<CSSPrimitiveValue> m_top;
     RefPtrWillBeMember<CSSPrimitiveValue> m_right;
     RefPtrWillBeMember<CSSPrimitiveValue> m_bottom;
     RefPtrWillBeMember<CSSPrimitiveValue> m_left;
 };
 
@@ skipping 57 matching lines @@
     }
 
     // NOTE: If adding fields to this class please make the RectBase trace
     // method virtual and add a trace method in this subclass tracing the new
     // fields.
 };
 
 } // namespace WebCore
 
 #endif // Rect_h