Revert of cc: Remove use of PassAs() and constructor-casting with scoped_ptr.

cc/animation/animation_unittest.cc

Index: cc/animation/animation_unittest.cc
diff --git a/cc/animation/animation_unittest.cc b/cc/animation/animation_unittest.cc
index 7b701784f8246cbcdb3bbf3e94ebbdf44fe0940a..378bb7e92d442bafe7f9c70fe82f0a8473ea5223 100644
--- a/cc/animation/animation_unittest.cc
+++ b/cc/animation/animation_unittest.cc
@@ -21,11 +21,12 @@
 scoped_ptr<Animation> CreateAnimation(double iterations,
                                       double duration,
                                       double playback_rate) {
-  scoped_ptr<Animation> to_return(
-      Animation::Create(make_scoped_ptr(new FakeFloatAnimationCurve(duration)),
-                        0,
-                        1,
-                        Animation::Opacity));
+  scoped_ptr<Animation> to_return(Animation::Create(
+      make_scoped_ptr(
+          new FakeFloatAnimationCurve(duration)).PassAs<AnimationCurve>(),
+      0,
+      1,
+      Animation::Opacity));
   to_return->set_iterations(iterations);
   to_return->set_playback_rate(playback_rate);
   return to_return.Pass();