Web Animations: Refactor KeyframeEffectModel to work via an InterpolationEffect.

Source/core/animation/AnimatableValue.h

Index: Source/core/animation/AnimatableValue.h
diff --git a/Source/core/animation/AnimatableValue.h b/Source/core/animation/AnimatableValue.h
index de043f52914d008fa49735beb49afe5c769ffdbd..58ce56e3cf02a7d787e17f18b3c832655c501856 100644
--- a/Source/core/animation/AnimatableValue.h
+++ b/Source/core/animation/AnimatableValue.h
@@ -31,13 +31,12 @@
 #ifndef AnimatableValue_h
 #define AnimatableValue_h
 
-#include "core/animation/AnimationEffect.h"
 #include "core/css/CSSValue.h"
 #include "wtf/RefCounted.h"
 
 namespace WebCore {
 
-class AnimatableValue : public AnimationEffect::CompositableValue {
+class AnimatableValue : public RefCounted<AnimatableValue> {
 public:
     virtual ~AnimatableValue() { }
 
@@ -61,9 +60,6 @@ public:
         return equals(&value);
     }
 
-    virtual bool dependsOnUnderlyingValue() const OVERRIDE FINAL { return false; }
-    virtual PassRefPtr<AnimatableValue> compositeOnto(const AnimatableValue*) const OVERRIDE FINAL { return takeConstRef(this); }
-
     bool isClipPathOperation() const { return type() == TypeClipPathOperation; }
     bool isColor() const { return type() == TypeColor; }
     bool isDouble() const { return type() == TypeDouble; }