Nonsense. It works fine on Github, Fastmail, Gandi... it doesn't work on Google because Google uses a different spec. That bug is about making Firefox compatible with the variation that Chrome/Google uses.
In this case, though, what happened is that Google implemented a different, earlier version of the spec than most everyone else. Mozilla is busy implementing that spec as well to bridge the gap.
I am kind of surprised that the sites you mention can implement the spec correctly but Facebook and Google can't.