Bug 1141884 - Trigger compositor smooth scrolling to snap points when APZ is enabled. r=mstange,kip

--HG--
extra : commitid : 9TdFTY6HI0a

dom/events/EventStateManager.cpp

@@ -2557,6 +2557,8 @@ EventStateManager::DoScrollText(nsIScrollableFrame* aScrollableFrame,
     case WidgetWheelEvent::SCROLL_DEFAULT:
       if (isDeltaModePixel) {
         mode = nsIScrollableFrame::NORMAL;
+      } else if (aEvent->mFlags.mHandledByAPZ) {
+        mode = nsIScrollableFrame::SMOOTH_MSD;
       } else {
         mode = nsIScrollableFrame::SMOOTH;
       }