Backout changeset b5e6116756b6 (wrong bug number).

gfx/layers/apz/src/APZCTreeManager.cpp

@@ -272,11 +272,8 @@ static EventRegions
 GetEventRegions(const LayerMetricsWrapper& aLayer)
 {
   if (aLayer.IsScrollInfoLayer()) {
-    ParentLayerIntRect compositionBounds(RoundedToInt(aLayer.Metrics().GetCompositionBounds()));
-    nsIntRegion hitRegion(ParentLayerIntRect::ToUntyped(compositionBounds));
-    EventRegions eventRegions(hitRegion);
-    eventRegions.mDispatchToContentHitRegion = eventRegions.mHitRegion;
-    return eventRegions;
+    return EventRegions(nsIntRegion(ParentLayerIntRect::ToUntyped(
+      RoundedToInt(aLayer.Metrics().GetCompositionBounds()))));
   }
   return aLayer.GetEventRegions();
 }