flow: add detection for infinite redirects

[alex3683]

It's possible to configure a flow in a way that it starts an infinite redirect loop, ultimately leading to a crash of the whole browser or at least of the active browser tab.
Apart from erroneous configuration of the flow it's also possible to programmatically start an infinite loop by means of a bad sequence of navigateRequest events.
It would be good to detect such an infinite loop and break out of it.

[alex3683]

One possible solution to detect programming errors is to check if the last 10 navigation events tooks place within a few seconds and if that's the case, assume an error. Infinite calls to redirect might be detected in another more deterministic way.