Implement left property animation on InvalidatableStyleInterpolation

Source/core/animation/Keyframe.h

 // 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.
 
 #ifndef Keyframe_h
 #define Keyframe_h
 
 #include "core/CoreExport.h"
 #include "core/animation/AnimationEffect.h"
 #include "core/animation/EffectModel.h"
@@ skipping 40 matching lines @@
     virtual bool isStringKeyframe() const { return false; }
 
     DEFINE_INLINE_VIRTUAL_TRACE() { }
 
     class PropertySpecificKeyframe : public NoBaseWillBeGarbageCollectedFinalized<PropertySpecificKeyframe> {
     public:
         virtual ~PropertySpecificKeyframe() { }
         double offset() const { return m_offset; }
         TimingFunction& easing() const { return *m_easing; }
         EffectModel::CompositeOperation composite() const { return m_composite; }
+        double underlyingFraction() const { return m_composite == EffectModel::CompositeReplace ? 0 : 1; }
+        virtual bool isNeutral() const { ASSERT_NOT_REACHED(); return false; }
         virtual PassOwnPtrWillBeRawPtr<PropertySpecificKeyframe> cloneWithOffset(double offset) const = 0;
 
         // FIXME: Remove this once CompositorAnimations no longer depends on AnimatableValues
         virtual void populateAnimatableValue(CSSPropertyID, Element&, const ComputedStyle* baseStyle) const { }
         virtual const PassRefPtrWillBeRawPtr<AnimatableValue> getAnimatableValue() const = 0;
 
         virtual bool isAnimatableValuePropertySpecificKeyframe() const { return false; }
         virtual bool isCSSPropertySpecificKeyframe() const { return false; }
         virtual bool isSVGPropertySpecificKeyframe() const { return false; }
 
@@ skipping 27 matching lines @@
     }
 
     double m_offset;
     EffectModel::CompositeOperation m_composite;
     RefPtr<TimingFunction> m_easing;
 };
 
 } // namespace blink
 
 #endif // Keyframe_h