The 2nd parameter is not defined on window.alert() but use in Drupal.AjaxCommands.prototype.alert()

Problem/Motivation

According to MDN, window.alert() has only 1 parameter.
Drupal.AjaxCommands.prototype.alert() is implemented below and the 2nd parameter has no affect on an alert dialog.

alert(ajax, response, status) {
  window.alert(response.text, response.title);
},

Proposed resolution

Like other window.alert() in /core/misc/ajax.es6.js, join title and text.