Thank you everyone for all your interesting thoughts and pointers re: the crisis that is web browsers.
A few general followups collected in one place:
1. "Servo is the future, we/you should target effort there" - I'm finding this argument more and more convincing as the line count of the amount of code I'm tallying that I'd like to be removed from FF keeps going up.
I am somewhat amazed/shocked by the rapid introduction (and the code size) of recent "features"