Consider reverting “allow child-index pseudos to select unparented elements” change #695
Description
Spec section: https://drafts.csswg.org/selectors-4/#child-index
Original CSS WG issue: https://www.w3.org/Style/CSS/Tracker/issues/317
Discussion: https://lists.w3.org/Archives/Public/www-style/2013Mar/thread.html#msg290
But see also https://lists.w3.org/Archives/Public/www-archive/2016Oct/0009.html
At the time when this spec change was made more than 3 years ago at a time, we had interoperability among all UAs on this: They all implemented the original spec requirements. And in the 3 years since, Gecko is the only engine that has changed to match the spec change. So interop on this has now regressed, and it’s not clear if there are even any Blink/WebKit/Edge browser bugs open to request those other browsers implement this change.
So it seems like consideration should be made about either reverting the change or else getting some browser bugs raised and making an effort to get back to interoperability on this.