Tracking for upcoming CSS4 Selectors. http://www.w3.org/TR/selectors4/
Should it block html5test (#802822)?
No. Any specific features that are specified in selectors4 and are part of html5test should block both bugs, though.
Also "CSS Selectors 4"
We should be considering implementing Selectors 4 changes (new features) from Selectors 3, into Stylo at this point.