style(service): fix eslint warnings in auth.service.js

Author: benmarten

templates/app/client/components/auth(auth)/auth.service.js

@@ -1,3 +1,4 @@
+/*global _*/
 'use strict';
 // @flow
 class _User {
@@ -185,9 +186,8 @@ export function AuthService($location, $http, $cookies, $q, appConfig, Util, Use
       * @param  {Function|*} callback - optional, function(is)
       * @return {Bool|Promise}
       */
-    isAdmin() {
-      return Auth.hasRole
-        .apply(Auth, [].concat.apply(['admin'], arguments));
+    isAdmin(...args) {
+      return Auth.hasRole(...Reflect.apply([].concat, ['admin'], args));
     },
 
      /**
@@ -196,6 +196,7 @@ export function AuthService($location, $http, $cookies, $q, appConfig, Util, Use
       * @return {Bool}
       */
     isAdminSync() {
+      // eslint-disable-next-line no-sync
       return Auth.hasRoleSync('admin');
     },