FS-11589 [verto_communicator]: removing es6 use to support old browsers syntax

html5/verto/verto_communicator/src/vertoControllers/controllers/MainController.js

@@ -77,10 +77,15 @@
        * Login the user to verto server and
        * redirects him to dialpad page.
        */
-      $rootScope.login = function(redirect, skipPreview = false) {
+      $rootScope.login = function(redirect, skipPreview) {
         if(redirect == undefined) {
           redirect = true;
         }
+
+        if(skipPreview == undefined) {
+          redirect == false;
+        }
+
         var connectCallback = function(v, connected) {
           $scope.$apply(function() {
           verto.data.connecting = false;