Chrome implemented and shipped an early draft and has, I believe, broken it multiple times since. What it shipped has significant security implications that are

Chrome implemented and shipped an early draft and has, I believe, broken it multiple times since. What it shipped has significant security implications that are handled poorly at best (mostly not at all). Firefox and Safari have said “you what!? No way we’re implementing that as it is”. And Safari are now implementing the safe and boring part of the spec, not the part that people actually want.