[selectors-4] drag and drop

[annevk]

In whatwg/html@3044a7e @pwnall and @domenic removed the dropzone global attribute due to it not gaining traction.

As it turns out this feature was supposed to work together with https://drafts.csswg.org/selectors/#drag-pseudos: https://www.w3.org/TR/2013/WD-selectors4-20130502/#drag-pseudos.

Without the dropzone attribute I don't think these psuedo-classes have a hook to use, so they probably need to be removed, unless I'm missing something.

(Credit: @fantasai in #2250.)

[annevk]

Related: whatwg/html#1824.

[fantasai]

Seems reasonable to me.

[css-meeting-bot]

The Working Group just discussed [selectors-4] drag and drop, and agreed to the following resolutions:

• RESOLVED: remove drop psuedo class

The full IRC log of that discussion

<dael> Topic: [selectors-4] drag and drop
<dael> github: https://github.com//issues/2257
<dael> astearns: Suggestion was drop the drop speudo call since they have nothing to hook into
<dael> florian: What happened to what they hooked into?
<dael> gsnedders: There was no implementation interest in it.
<dael> astearns: Tehre was a drop zone global attribute that wasn't gaining traction so they removed it.
<dael> astearns: Objections to removing drop psuedo class for now?
<dael> RESOLVED: remove drop psuedo class