[Reland] Web Animations: Introduce String based KeyframeEffectModel

Source/core/animation/Interpolation.cpp

 // 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 "config.h"
 #include "core/animation/Interpolation.h"
 
+#include "core/animation/AnimatableDouble.h"
 #include "core/css/resolver/AnimatedStyleBuilder.h"
 #include "core/css/resolver/StyleResolverState.h"
 
 namespace WebCore {
 
 DEFINE_EMPTY_DESTRUCTOR_WILL_BE_REMOVED(Interpolation);
 
 namespace {
 
 bool typesMatch(const InterpolableValue* start, const InterpolableValue* end)
@@ skipping 45 matching lines @@
     visitor->trace(m_cachedValue);
 }
 
 void StyleInterpolation::trace(Visitor* visitor)
 {
     Interpolation::trace(visitor);
 }
 
 void LegacyStyleInterpolation::apply(StyleResolverState& state) const
 {
-    AnimatableValue* value = currentValue();
-    AnimatedStyleBuilder::applyProperty(m_id, state, value);
+    AnimatedStyleBuilder::applyProperty(m_id, state, currentValue().get());
 }
 
 void LegacyStyleInterpolation::trace(Visitor* visitor)
 {
     StyleInterpolation::trace(visitor);
 }
 
 }