Allow Selenium using the performance timing API
We want to have some measurements about various stages of a page load when using Selenium to instrument Tor Browser. Right now, in order to use things like the Navigation Timing API we have to fully disable Resist Fingerprinting Mode which is unfortunate as it does not give us a Tor Browser as users are having which is skewing our measurements results.
We should make it possible to enable selected features we disable with Resist Fingerprinting Mode if run, say, in a testing environment.