--- a/gfx/layers/composite/ContainerLayerComposite.cpp
+++ b/gfx/layers/composite/ContainerLayerComposite.cpp
@@ -157,18 +157,18 @@ static gfx::IntRect ContainerVisibleRect
 }
 
 
 /* all of the per-layer prepared data we need to maintain */
 struct PreparedLayer
 {
   PreparedLayer(LayerComposite *aLayer,
                 RenderTargetIntRect aClipRect,
-                Maybe<gfx::Polygon>&& aGeometry)
-  : mLayer(aLayer), mClipRect(aClipRect), mGeometry(Move(aGeometry)) {}
+                const Maybe<gfx::Polygon>& aGeometry)
+  : mLayer(aLayer), mClipRect(aClipRect), mGeometry(aGeometry) {}
 
   LayerComposite* mLayer;
   RenderTargetIntRect mClipRect;
   Maybe<Polygon> mGeometry;
 };
 
 /* all of the prepared data that we need in RenderLayer() */
 struct PreparedData
@@ -187,20 +187,20 @@ ContainerPrepare(ContainerT* aContainer,
   aContainer->mPrepared = MakeUnique<PreparedData>();
   aContainer->mPrepared->mNeedsSurfaceCopy = false;
 
   const ContainerLayerComposite::SortMode sortMode =
     aManager->GetCompositor()->SupportsLayerGeometry()
     ? ContainerLayerComposite::SortMode::WITH_GEOMETRY
     : ContainerLayerComposite::SortMode::WITHOUT_GEOMETRY;
 
-  nsTArray<LayerPolygon> polygons =
+  const nsTArray<LayerPolygon> polygons =
     aContainer->SortChildrenBy3DZOrder(sortMode);
 
-  for (LayerPolygon& layer : polygons) {
+  for (const LayerPolygon& layer : polygons) {
     LayerComposite* layerToRender =
       static_cast<LayerComposite*>(layer.layer->ImplData());
 
     RenderTargetIntRect clipRect =
       layerToRender->GetLayer()->CalculateScissorRect(aClipRect);
 
     if (layerToRender->GetLayer()->IsBackfaceHidden()) {
       continue;
@@ -219,18 +219,17 @@ ContainerPrepare(ContainerT* aContainer,
         CULLING_LOG("Sublayer %p has an empty world clip rect\n", layerToRender->GetLayer());
         continue;
       }
     }
 
     CULLING_LOG("Preparing sublayer %p\n", layerToRender->GetLayer());
 
     layerToRender->Prepare(clipRect);
-    aContainer->mPrepared->mLayers.AppendElement(PreparedLayer(layerToRender, clipRect,
-                                                               Move(layer.geometry)));
+    aContainer->mPrepared->mLayers.AppendElement(PreparedLayer(layerToRender, clipRect, layer.geometry));
   }
 
   CULLING_LOG("Preparing container layer %p\n", aContainer->GetLayer());
 
   /**
    * Setup our temporary surface for rendering the contents of this container.
    */