If you use $timeout to perform any operation on a set interval in your application, then the 'browseTo' step never completes.

Minimal demonstration here:

http://plnkr.co/edit/iW3dHM?p=preview

Note that the test application is not hung in the scenario runner iframe, it's just that browseTo never completes.

Problem seems to be with the way that the scenario runner tries to make sure that all async operations are complete before advancing to the next step. outstandingRequestCount never decrements to zero because the $timeout callback reschedules itself.