background: Trivial style cleanup

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1599>

js/ui/background.js

@@ -655,12 +655,14 @@ class Animation extends GnomeDesktop.BGSlideShow {
 
 var BackgroundManager = class BackgroundManager {
     constructor(params) {
-        params = Params.parse(params, { container: null,
+        params = Params.parse(params, {
+            container: null,
             layoutManager: Main.layoutManager,
             monitorIndex: null,
             vignette: false,
             controlPosition: true,
-                                        settingsSchema: BACKGROUND_SCHEMA });
+            settingsSchema: BACKGROUND_SCHEMA,
+        });
 
         let cache = getBackgroundCache();
         this._settingsSchema = params.settingsSchema;