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

cc/blink/web_float_animation_curve_impl.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/blink/web_float_animation_curve_impl.h"
 
 #include "cc/animation/animation_curve.h"
 #include "cc/animation/keyframed_animation_curve.h"
 #include "cc/animation/timing_function.h"
 #include "cc/blink/web_animation_curve_common.h"
@@ skipping 25 matching lines @@
 }
 
 void WebFloatAnimationCurveImpl::add(const WebFloatKeyframe& keyframe,
                                      double x1,
                                      double y1,
                                      double x2,
                                      double y2) {
   curve_->AddKeyframe(cc::FloatKeyframe::Create(
       keyframe.time,
       keyframe.value,
-      cc::CubicBezierTimingFunction::Create(x1, y1, x2, y2)));
+      cc::CubicBezierTimingFunction::Create(x1, y1, x2, y2)
+          .PassAs<cc::TimingFunction>()));
 }
 
 float WebFloatAnimationCurveImpl::getValue(double time) const {
   return curve_->GetValue(time);
 }
 
 scoped_ptr<cc::AnimationCurve>
 WebFloatAnimationCurveImpl::CloneToAnimationCurve() const {
   return curve_->Clone();
 }
 
 }  // namespace cc_blink