Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/platform/fonts/mac/MemoryActivatedFont.mm

 /*
  * This file is part of the internal font implementation.
  *
  * Copyright (c) 2010 Google 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.
  *
@@ skipping 100 matching lines @@
 
     CGFontRef tmpCGFont;
     uint32_t fontID;
     // Send cross-process request to load font.
     blink::WebSandboxSupport* sandboxSupport = blink::Platform::current()->sandboxSupport();
     if (!sandboxSupport) {
         // This function should only be called in response to an error loading a
         // font due to being blocked by the sandbox.
         // This by definition shouldn't happen if there is no sandbox support.
         ASSERT_NOT_REACHED();
-        return 0;
+        return nullptr;
     }
     if (!sandboxSupport->loadFont(nsFont, &tmpCGFont, &fontID))
-        return 0;
+        return nullptr;
 
     RetainPtr<CGFontRef> cgFont(tmpCGFont);
     // Now that we have the fontID from the browser process, we can consult
     // the ID cache.
     font = fontCacheByFontID().get(fontID);
     if (font)
         // FIXME: WebSandboxSupport::loadFont() should consult the id cache
         // before activating the font.
         return font;
 
@@ skipping 63 matching lines @@
             // are consistent.
             CFRetain(cgFont);
         } else {
             // If we still can't load the font, set |outNSFont| to null so that FontPlatformData won't be used.
             outNSFont = 0;
         }
     }
 }
 
 } // namespace WebCore