Bug 1267438 - Remove the (no longer used) isClipFixed=false annotation. r=mstange

MozReview-Commit-ID: LicG7zFHnX3

layout/base/FrameLayerBuilder.cpp

@@ -4883,7 +4883,7 @@ ContainerState::PostprocessRetainedLayers(nsIntRegion* aOpaqueRegionForContainer
       if (clipRect) {
         clippedOpaque.AndWith(clipRect->ToUnknownRect());
       }
-      if (e->mLayer->GetIsFixedPosition() && !e->mLayer->IsClipFixed()) {
+      if (e->mLayer->GetIsFixedPosition() && e->mLayer->GetScrolledClip()) {
         // The clip can move asynchronously, so we can't rely on opaque parts
         // staying in the same place.
         clippedOpaque.SetEmpty();