The point of calling "register" in the test was because we want to start listening to events at one specific point in time.

That said, I see that we're always calling "register" after loading the file, so maybe there is no point in doing it that way. I guess it was only to be symmetrical with "unregister". Was it really producing the bug, or was it more the calls to marionetteScriptFinished in non-asynced scripts?