Bug 1292441 - Part 1: Avoid crashes when 'reftest-opaque-layer' is specified against an element having an display item which is not assigned to a PaintedLayer. r=mstange

MozReview-Commit-ID: HISvrzIwUZ2

--HG--
extra : rebase_source : da0c2e25d529ce6bf82d38f434301eb0f0f62503

layout/base/FrameLayerBuilder.cpp

@@ -2047,6 +2047,11 @@ FrameLayerBuilder::GetDebugSingleOldPaintedLayerForFrame(nsIFrame* aFrame)
     }
     layer = data->mLayer;
   }
+
+  if (!layer) {
+    return nullptr;
+  }
+
   return layer->AsPaintedLayer();
 }