Bug 1521644 - Do not place the RCD-RSF scroll clip onto the layers with RCD-RSF scroll metadata in containerless mode. r=mstange

The clip will go onto the async zoom container layer instead.

Differential Revision: https://phabricator.services.mozilla.com/D17169

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

layout/generic/nsGfxScrollFrame.cpp

@@ -3886,9 +3886,7 @@ Maybe<ScrollMetadata> ScrollFrameHelper::ComputeScrollMetadata(
       mOuter->GetOffsetToCrossDoc(aContainerReferenceFrame);
 
   Maybe<nsRect> parentLayerClip;
-  // For containerful frames, the clip is on the container layer.
-  if (aClip &&
-      (!gfxPrefs::LayoutUseContainersForRootFrames() || mAddClipRectToLayer)) {
+  if (aClip && mAddClipRectToLayer) {
     parentLayerClip = Some(aClip->GetClipRect());
   }