style: Allow lonely ifs where appropriate

We now have a lint rule to disallow lonely ifs, however there are
cases where the "lonely" part mirrors code from the preceding if
clause. Opt out of the lint rule in those cases.

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/818

js/gdm/util.js

@@ -544,6 +544,7 @@ var ShellUserVerifier = class {
                 });
             }
         } else {
+            // eslint-disable-next-line no-lonely-if
             if (!this.hasPendingMessages) {
                 this._cancelAndReset();
             } else {