Remove ScrollableArea::notifyScrollPositionChanged and cleanup scroll animators.

Source/platform/scroll/ProgrammaticScrollAnimator.h

Index: Source/platform/scroll/ProgrammaticScrollAnimator.h
diff --git a/Source/platform/scroll/ProgrammaticScrollAnimator.h b/Source/platform/scroll/ProgrammaticScrollAnimator.h
index ef1c60c87e30ce90bebd6db8bdfec2704f3dd649..d3813a33eb54555fc19179f72864ed75820add85 100644
--- a/Source/platform/scroll/ProgrammaticScrollAnimator.h
+++ b/Source/platform/scroll/ProgrammaticScrollAnimator.h
@@ -26,6 +26,7 @@ public:
 
     ~ProgrammaticScrollAnimator();
 
+    void scrollToOffsetWithoutAnimation(const FloatPoint&);
     void animateToOffset(FloatPoint);
     void cancelAnimation();
     void tickAnimation(double monotonicTime);
@@ -58,6 +59,7 @@ private:
     };
 
     void resetAnimationState();
+    void notifyPositionChanged(const DoublePoint&);
 
     ScrollableArea* m_scrollableArea;
     OwnPtr<WebScrollOffsetAnimationCurve> m_animationCurve;