refactor: used loaded over mounted

packages/pinball_components/lib/src/components/layer.dart

@@ -21,8 +21,7 @@ mixin Layered<T extends Forge2DGame> on BodyComponent<T> {
   set layer(Layer value) {
     _layer = value;
     if (!isLoaded) {
-      // TODO(alestiago): Use loaded.whenComplete once provided.
+      loaded.whenComplete(_applyMaskBits);
-      mounted.whenComplete(_applyMaskBits);
     } else {
       _applyMaskBits();
     }