Handling exception UnexpectedAlertOpen thrown when browser displays an alert

Sadly there are projects that still using native js alerts. I've noticed that when browser shows an alert, I don't have any chance to interact to the modal because an exception is raised by HttpCallListener.

These steps worked few weeks ago.

```
    When I go to subscription details page
    And wait 10 seconds until I see "Subscription Details"
    # this steps will show a js alert
    And I follow "Cancel subscription"
   # this step will assert the message and accept it
    And I accept subscription cancel alert
```