Also, all the discussion so far seems to focus on desktop firefox, are these improvements coming to firefox for android, or is that a longer term project, perhaps when servo is ready?
I can turn on `layout.css.servo.enabled`, on Firefox 55 Android (and Desktop). What does it mean? If I understand correctly, Firefox will have this property turned on by default in 57/58 but it's possible to have it early?
No, it won't do anything on 55. Or on 56/57 Android.
Stylo can be disabled at build time, and this was the case for 55 and is still the case for android. We don't remove the associated prefs in that case (about:config doesn't have UX because it's not exactly user facing).
You can go to about:support to see if stylo is actually enabled. There's a "stylo" column. It's not there in 55, but no 55 release has stylo enabled at build time; so if you don't have that column at all, stylo isn't there.
There's more to putting it in the product than just the code, but the style system in Servo does already work on Android. Once 57 ships, I suspect there will be some resources to start doing the remaining product integration work for Firefox on Android.
