If nobody implements or plans to implement or is seriously advocating for the CSSStyleDeclaration style attribute, then I'd like to remove it. Otherwise I think we've stripped this down to the minimum at this point... @birtles any comment?

@heycam writes...

I wonder if we should leave ::selection off this list. It feels like a pretty different thing from ::before, ::after, ::first-letter, and ::first-line, all of which basically have a box corresponding to them (at least for Gecko). Or would it be allowed to return a CSSPseudoElement for ::selection but not to support e.g. Web Animations targeting it?

So another question is what we want to support wrt ::selection here. See also #3607 and #3603 which might inform this decision.

We don't have any specific plans at this point to implement any more than:

[Exposed=Window]
interface CSSPseudoElement {
    readonly attribute CSSOMString type;
    readonly attribute Element element;
};

Furthermore, for type we only support ::before and ::after. We don't implement Element.pseudo() either or have any specific plans to do so but it might be worth doing just to clarify the identity issues @heycam raised since they probably affect what we currently return.

(In our implementation the only way to get a CSSPseudoElement is to create a CSS animation / transition on a pseudo, then call getAnimations() and fetch the effect.target of the returned CSSAnimation or CSSTransition.)

The CSS Working Group just discussed Mark unimplemented CSSPseudoElement features at-risk, and agreed to the following:

• RESOLVED: Drop style from this level, restrict API to ::before and ::after, add a note to why the other things are not yet supported