Attempt to fix the crash in blink Scroll Animator.

third_party/WebKit/Source/platform/scroll/ScrollAnimatorBase.h

Index: third_party/WebKit/Source/platform/scroll/ScrollAnimatorBase.h
diff --git a/third_party/WebKit/Source/platform/scroll/ScrollAnimatorBase.h b/third_party/WebKit/Source/platform/scroll/ScrollAnimatorBase.h
index 50cc5f2fa8d2e53c843283a927839657cc794872..7b3c1657dd44e189cdce070950bcb4a47b015d80 100644
--- a/third_party/WebKit/Source/platform/scroll/ScrollAnimatorBase.h
+++ b/third_party/WebKit/Source/platform/scroll/ScrollAnimatorBase.h
@@ -54,6 +54,8 @@ public:
 
     virtual void dispose() { }
 
+    virtual void clearScrollAnimator() { return ScrollAnimatorCompositorCoordinator::dispose(); }
+
     // Computes a scroll destination for the given parameters.  The returned
     // ScrollResultOneDimensional will have didScroll set to false if already at
     // the destination.  Otherwise, starts scrolling towards the destination and