Add foundation for removing AnimatableValues from StyleInterpolation

Source/core/animation/KeyframeEffectModel.h

Index: Source/core/animation/KeyframeEffectModel.h
diff --git a/Source/core/animation/KeyframeEffectModel.h b/Source/core/animation/KeyframeEffectModel.h
index aec30e83de7780902b62337b43adc083fcf49c39..b491ff799af09d660ae8a01286d335551375c2fa 100644
--- a/Source/core/animation/KeyframeEffectModel.h
+++ b/Source/core/animation/KeyframeEffectModel.h
@@ -56,10 +56,10 @@ class CORE_EXPORT KeyframeEffectModelBase : public EffectModel {
 public:
     // FIXME: Implement accumulation.
 
-    using PropertySpecificKeyframeVector = WillBeHeapVector<OwnPtrWillBeMember<Keyframe::PropertySpecificKeyframe>>;
+    using PropertySpecificKeyframeVector = WillBeHeapVector<RefPtrWillBeMember<Keyframe::PropertySpecificKeyframe>>;
     class PropertySpecificKeyframeGroup : public NoBaseWillBeGarbageCollected<PropertySpecificKeyframeGroup> {
     public:
-        void appendKeyframe(PassOwnPtrWillBeRawPtr<Keyframe::PropertySpecificKeyframe>);
+        void appendKeyframe(PassRefPtrWillBeRawPtr<Keyframe::PropertySpecificKeyframe>);
         const PropertySpecificKeyframeVector& keyframes() const { return m_keyframes; }
 
         DECLARE_TRACE();