Delete unused AnimatableValue code

third_party/WebKit/Source/core/animation/animatable/AnimatableVisibility.h

Index: third_party/WebKit/Source/core/animation/animatable/AnimatableVisibility.h
diff --git a/third_party/WebKit/Source/core/animation/animatable/AnimatableVisibility.h b/third_party/WebKit/Source/core/animation/animatable/AnimatableVisibility.h
index 2eaf8ffa57fdc298e8366c64672a994cb03ca311..0b0ee470c903b5a5b60463c2db2917a6010dc6dc 100644
--- a/third_party/WebKit/Source/core/animation/animatable/AnimatableVisibility.h
+++ b/third_party/WebKit/Source/core/animation/animatable/AnimatableVisibility.h
@@ -37,20 +37,13 @@
 
 namespace blink {
 
-class CORE_EXPORT AnimatableVisibility final : public AnimatableValue {
+class AnimatableVisibility final : public AnimatableValue {
  public:
   ~AnimatableVisibility() override {}
   static PassRefPtr<AnimatableVisibility> create(EVisibility visibility) {
     return adoptRef(new AnimatableVisibility(visibility));
   }
 
-  EVisibility visibility() const { return m_visibility; }
-
- protected:
-  PassRefPtr<AnimatableValue> interpolateTo(const AnimatableValue*,
-                                            double fraction) const override;
-  bool usesDefaultInterpolationWith(const AnimatableValue*) const override;
-
  private:
   explicit AnimatableVisibility(EVisibility visibility)
       : m_visibility(visibility) {}