Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/modules/geolocation/Geolocation.cpp

 /*
  * Copyright (C) 2008, 2009, 2010, 2011 Apple Inc. All Rights Reserved.
  * Copyright (C) 2009 Torch Mobile, Inc.
  * Copyright 2010, The Android Open Source Project
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 27 matching lines @@
 
 namespace WebCore {
 
 static const char permissionDeniedErrorMessage[] = "User denied Geolocation";
 static const char failedToStartServiceErrorMessage[] = "Failed to start Geolocation service";
 static const char framelessDocumentErrorMessage[] = "Geolocation cannot be used in frameless documents";
 
 static PassRefPtrWillBeRawPtr<Geoposition> createGeoposition(GeolocationPosition* position)
 {
     if (!position)
-        return 0;
+        return nullptr;
 
     RefPtrWillBeRawPtr<Coordinates> coordinates = Coordinates::create(
         position->latitude(),
         position->longitude(),
         position->canProvideAltitude(),
         position->altitude(),
         position->accuracy(),
         position->canProvideAltitudeAccuracy(),
         position->altitudeAccuracy(),
         position->canProvideHeading(),
@@ skipping 646 matching lines @@
                 notifier->startTimerIfNeeded();
             else
                 notifier->setFatalError(PositionError::create(PositionError::POSITION_UNAVAILABLE, failedToStartServiceErrorMessage));
         } else {
             notifier->setFatalError(PositionError::create(PositionError::PERMISSION_DENIED, permissionDeniedErrorMessage));
         }
     }
 }
 
 } // namespace WebCore