The original YesScript was the only legacy extension I was worried about losing when moving to FireFox 57. IMO, being able to blacklist specific domains from running scripts (if you pay attention, you'll notice most ad-heavy websites are displaying ads from the same set of domains using iframes) is must-have functionality for browsing the web (some other browsers -- which I won't name here -- have this built-in).

With the latest update to version 2.5 (applies script blocking policy to pages loaded in iframes), YesScript2 does everything I used the original YesScript for. I also like the way YesScript2 handles the blocklist better than the original. In the original YesScript, you had to add an entry for http and https if you wanted to block both. YesScript2 just needs one entry for a domain.

I guess it's a feature of the new WebExtensions but it's also cool that I didn't have to restart Firefox after updating.