--- a/layout/painting/nsDisplayList.h
+++ b/layout/painting/nsDisplayList.h
@@ -3993,17 +3993,16 @@ public:
     nsDisplayItem::RemoveFrame(aFrame);
   }
 
 protected:
   typedef class mozilla::layers::ImageContainer ImageContainer;
   typedef class mozilla::layers::ImageLayer ImageLayer;
 
   bool CanBuildWebRenderDisplayItems(LayerManager* aManager);
-  bool TryOptimizeToImageLayer(LayerManager* aManager, nsDisplayListBuilder* aBuilder);
   nsRect GetBoundsInternal(nsDisplayListBuilder* aBuilder,
                            nsIFrame* aFrameForBounds = nullptr);
 
   void PaintInternal(nsDisplayListBuilder* aBuilder, gfxContext* aCtx,
                      const nsRect& aBounds, nsRect* aClipRect);
 
   // Determine whether we want to be separated into our own layer, independent
   // of whether this item can actually be layerized.