code: function isPermitted() {
    var permitted = {
      granted: function allow() {
        return Promise.resolve(true);
      },
      denied: function deny() {
        return Promise.resolve(false);
      },
      default: function ask() {
        return Notification.requestPermission().then(function(permission) {
          return permission === 'granted';
        });
      }
    };
  
    return permitted[Notification.permission]();
  }
docs: Checks if browser notification is permitted by user.
  
  @private
  @see {@link https://developer.mozilla.org/en-US/docs/Web/API/Notification/permission|Notification.permission}
  @see {@link Mocha#growl}
  @see {@link Mocha#isGrowlPermitted}
  @returns {Promise<boolean>} promise determining if browser notification
  permissible when fulfilled.