Open
Description
Background is the discussion in #4437.
As of that change, KeyframeEffect
now has a pseudoElement
member whose syntax is defined by Selectors Level 4.
That definition requires UAs to accept the old single colon syntax (:before
) as well as the double colon syntax (::before
).
I was under the impression we wanted to phase that historical artifact out of the web platform so that new APIs like this should reject :before
and only accept ::before
.