Bug 1577190. Don't treat Mask items like Filter items in DetectContainerLayerPropertiesBoundsChange. r=nical,mstange

This is a remnant from the previous implementation of masking. That
implementation was replaced in bug 1447880.

Differential Revision: https://phabricator.services.mozilla.com/D43763

--HG--
extra : moz-landing-system : lando

gfx/layers/wr/WebRenderCommandBuilder.cpp

@@ -266,16 +266,10 @@ static bool IsContainerLayerItem(nsDisplayItem* aItem) {
 static bool DetectContainerLayerPropertiesBoundsChange(
     nsDisplayItem* aItem, BlobItemData* aData,
     nsDisplayItemGeometry& aGeometry) {
-  switch (aItem->GetType()) {
+  if (aItem->GetType() == DisplayItemType::TYPE_FILTER) {
-    case DisplayItemType::TYPE_MASK:
+    // Filters go through BasicLayerManager composition which clips to
-    case DisplayItemType::TYPE_FILTER: {
+    // the BuildingRect
-      // These two items go through BasicLayerManager composition which clips to
+    aGeometry.mBounds = aGeometry.mBounds.Intersect(aItem->GetBuildingRect());
-      // the BuildingRect
-      aGeometry.mBounds = aGeometry.mBounds.Intersect(aItem->GetBuildingRect());
-      break;
-    }
-    default:
-      break;
   }
 
   return !aGeometry.mBounds.IsEqualEdges(aData->mGeometry->mBounds);