cc: Delete unused AnimationCurve::AffectsScale and related code

cc/animation/animation_curve.h

Index: cc/animation/animation_curve.h
diff --git a/cc/animation/animation_curve.h b/cc/animation/animation_curve.h
index a54480c5e8ca77c6954ad06abe1037f62e62d439..c52ff180039af8609514d0877615430e927c209f 100644
--- a/cc/animation/animation_curve.h
+++ b/cc/animation/animation_curve.h
@@ -77,9 +77,6 @@ class CC_EXPORT TransformAnimationCurve : public AnimationCurve {
   virtual bool AnimatedBoundsForBox(const gfx::BoxF& box,
                                     gfx::BoxF* bounds) const = 0;
 
-  // Returns true if this animation affects scale.
-  virtual bool AffectsScale() const = 0;
-
   // Returns true if this animation is a translation.
   virtual bool IsTranslation() const = 0;