Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/rendering/RenderThemeChromiumMac.mm

 /*
  * Copyright (C) 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Google, 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.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 722 matching lines @@
 
     NSFont* font = [NSFont systemFontOfSize:[NSFont systemFontSizeForControlSize:controlSize]];
     fontDescription.firstFamily().setFamily([font webCoreFamilyName]);
     fontDescription.setComputedSize([font pointSize] * style->effectiveZoom());
     fontDescription.setSpecifiedSize([font pointSize] * style->effectiveZoom());
 
     // Reset line height
     style->setLineHeight(RenderStyle::initialLineHeight());
 
     if (style->setFontDescription(fontDescription))
-        style->font().update(0);
+        style->font().update(nullptr);
 }
 
 NSControlSize RenderThemeChromiumMac::controlSizeForSystemFont(RenderStyle* style) const
 {
     float fontSize = style->fontSize();
     float zoomLevel = style->effectiveZoom();
     if (zoomLevel != 1)
         fontSize /= zoomLevel;
     if (fontSize >= [NSFont systemFontSizeForControlSize:NSRegularControlSize])
         return NSRegularControlSize;
@@ skipping 1261 matching lines @@
 
 bool RenderThemeChromiumMac::shouldUseFallbackTheme(RenderStyle* style) const
 {
     ControlPart part = style->appearance();
     if (part == CheckboxPart || part == RadioPart)
         return style->effectiveZoom() != 1;
     return false;
 }
 
 } // namespace WebCore