Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/animation/CompositorAnimationsTest.cpp

 /*
  * Copyright (c) 2013, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 164 matching lines @@
     {
         KeyframeEffectModel::KeyframeVector frames;
         for (size_t i = 0; i < values.size(); i++) {
             double offset = 1.0 / (values.size() - 1) * i;
             RefPtr<AnimatableDouble> value = AnimatableDouble::create(values[i]);
             frames.append(createReplaceOpKeyframe(CSSPropertyOpacity, value.get(), offset).get());
         }
         return frames;
     }
 
-    PassRefPtr<KeyframeEffectModel> createKeyframeEffectModel(PassRefPtr<Keyframe> prpFrom, PassRefPtr<Keyframe> prpTo, PassRefPtr<Keyframe> prpC = 0, PassRefPtr<Keyframe> prpD = 0)
+    PassRefPtr<KeyframeEffectModel> createKeyframeEffectModel(PassRefPtr<Keyframe> prpFrom, PassRefPtr<Keyframe> prpTo, PassRefPtr<Keyframe> prpC = nullptr, PassRefPtr<Keyframe> prpD = nullptr)
     {
         RefPtr<Keyframe> from = prpFrom;
         RefPtr<Keyframe> to = prpTo;
         RefPtr<Keyframe> c = prpC;
         RefPtr<Keyframe> d = prpD;
 
         EXPECT_EQ(from->offset(), 0);
         KeyframeEffectModel::KeyframeVector frames;
         frames.append(from);
         EXPECT_LE(from->offset(), to->offset());
@@ skipping 840 matching lines @@
     // Go!
     setCompositorForTesting(mockCompositor);
     Vector<OwnPtr<blink::WebAnimation> > result;
     getAnimationOnCompositor(m_timing, *effect.get(), result);
     EXPECT_EQ(1U, result.size());
     result[0].clear();
 }
 
 
 } // namespace WebCore