Don't update graphics layer positions during coordinated scrolling

Source/core/page/scrolling/ScrollingCoordinator.cpp

Index: Source/core/page/scrolling/ScrollingCoordinator.cpp
diff --git a/Source/core/page/scrolling/ScrollingCoordinator.cpp b/Source/core/page/scrolling/ScrollingCoordinator.cpp
index fdca37469a2c4d2bc37cf3636d19ea8aaf05bf26..7f9a9c75bfbb36f8888fdbcddeae872b1cf49f81 100644
--- a/Source/core/page/scrolling/ScrollingCoordinator.cpp
+++ b/Source/core/page/scrolling/ScrollingCoordinator.cpp
@@ -267,7 +267,7 @@ void ScrollingCoordinator::scrollableAreaScrollbarLayerDidChange(ScrollableArea*
         removeWebScrollbarLayer(scrollableArea, orientation);
 }
 
-void ScrollingCoordinator::scrollableAreaScrollLayerDidChange(ScrollableArea* scrollableArea)
+bool ScrollingCoordinator::scrollableAreaScrollLayerDidChange(ScrollableArea* scrollableArea)
 {
     GraphicsLayer* scrollLayer = scrollLayerForScrollableArea(scrollableArea);
     if (scrollLayer)
@@ -283,6 +283,8 @@ void ScrollingCoordinator::scrollableAreaScrollLayerDidChange(ScrollableArea* sc
         setupScrollbarLayer(horizontalScrollbarLayerForScrollableArea(scrollableArea), scrollbarLayer, webLayer);
     if (WebScrollbarLayer* scrollbarLayer = getWebScrollbarLayer(scrollableArea, VerticalScrollbar))
         setupScrollbarLayer(verticalScrollbarLayerForScrollableArea(scrollableArea), scrollbarLayer, webLayer);
+
+    return !!webLayer;
 }
 
 void ScrollingCoordinator::setTouchEventTargetRects(const Vector<IntRect>& absoluteHitTestRects)