cleanup: Avoid useless return statements

Return statements are only useful if they return a value or break
the regular function flow (i.e. early returns). Remove all returns
that do neither.

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/731

js/gdm/batch.js

@@ -202,7 +202,6 @@ var ConsecutiveBatch = class extends Batch {
                 hold.disconnect(signalId);
                 this.nextTask();
             });
-            return;
         } else {
             // This task finished, process the next one
             this.nextTask();