Reporting on unexpected alerts

A modest improvement to detect unexpected alerts:

**Firefox, unexpected alert:** Selenium closes the alert and tests proceed. Eventually we get a report of the alert and our guess of the "nearest" spec is not as accurate as I'd like (could improve accuracy by reducing the sleep call)

**Firefox, unresponsive script:** reports this quite well, seems to reliably report the finished spec right before the unresponsive script. Kills off the tests from here and ends the job once detected

**Chrome, unexpected alert:** We close the alert ourself and move on with the tests. The report of "nearest" for the alert is pretty good

**Chrome: unresponsive script:** does not happen. Chrome in the selenium environment never complains. It will happily sit in an infinite loop forever.