cleanup: Remove some unhelpful unused arguments

Those unused arguments aren't bugs - unbeknownst to eslint, they all
correspond to valid signal parameters - but they don't contribute
anything to clarity, so just remove them anyway.

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/627

js/ui/lookingGlass.js

@@ -267,7 +267,7 @@ var ObjLink = class ObjLink {
         this._lookingGlass = lookingGlass;
     }
 
-    _onClicked(link) {
+    _onClicked() {
         this._lookingGlass.inspectObject(this._obj, this.actor);
     }
 };