Notify ProgrammaticScrollAnimator about scroll layer destruction

Source/core/page/scrolling/ScrollingCoordinator.cpp

 /*
  * Copyright (C) 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 397 matching lines @@
     if (WebScrollbarLayer* scrollbarLayer = getWebScrollbarLayer(scrollableArea, VerticalScrollbar)) {
         GraphicsLayer* verticalScrollbarLayer = scrollableArea->layerForVerticalScrollbar();
         if (verticalScrollbarLayer)
             setupScrollbarLayer(verticalScrollbarLayer, scrollbarLayer, webLayer, containerLayer);
     }
 
     // Update the viewport layer registration if the outer viewport may have changed.
     if (m_page->settings().rootLayerScrolls() && isForRootLayer(scrollableArea))
         m_page->chrome().registerViewportLayers();
 
+    scrollableArea->layerForScrollingDidChange();
+
     return !!webLayer;
 }
 
 using GraphicsLayerHitTestRects = WTF::HashMap<const GraphicsLayer*, Vector<LayoutRect>>;
 
 // In order to do a DFS cross-frame walk of the RenderLayer tree, we need to know which
 // RenderLayers have child frames inside of them. This computes a mapping for the
 // current frame which we can consult while walking the layers of that frame.
 // Whenever we descend into a new frame, a new map will be created.
 using LayerFrameMap = HashMap<const RenderLayer*, Vector<const LocalFrame*>>;
@@ skipping 604 matching lines @@
     bool frameIsScrollable = frameView && frameView->isScrollable();
     if (frameIsScrollable != m_wasFrameScrollable)
         return true;
 
     if (WebLayer* scrollLayer = frameView ? toWebLayer(frameView->layerForScrolling()) : nullptr)
         return blink::WebSize(frameView->contentsSize()) != scrollLayer->bounds();
     return false;
 }
 
 } // namespace blink