Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/rendering/RenderTheme.cpp

 /**
  * This file is part of the theme implementation for form controls in WebCore.
  *
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Computer, 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 170 matching lines @@
             style->setMinHeight(minControlSize.height());
 
         // Font
         FontDescription controlFont = m_platformTheme->controlFont(part, style->font().fontDescription(), style->effectiveZoom());
         if (controlFont != style->font().fontDescription()) {
             // Reset our line-height
             style->setLineHeight(RenderStyle::initialLineHeight());
 
             // Now update our font.
             if (style->setFontDescription(controlFont))
-                style->font().update(0);
+                style->font().update(nullptr);
         }
     }
     default:
         break;
     }
 #endif
 
     // Call the appropriate style adjustment method based off the appearance value.
     switch (style->appearance()) {
 #if !USE(NEW_THEME)
@@ skipping 1065 matching lines @@
 
     // padding - not honored by WinIE, needs to be removed.
     style->resetPadding();
 
     // border - honored by WinIE, but looks terrible (just paints in the control box and turns off the Windows XP theme)
     // for now, we will not honor it.
     style->resetBorder();
 }
 
 } // namespace WebCore