From: Erik Arvidsson [mailto:a...@google.com]
> I'm not sure how that is speced but in Blink we have an extended IDL > attribute called CustomElementCallbacks which means that we are going to call > the pending callbacks after the method/setter. If I recall this is how Anne and others were saying that it *should* be specced, but the spec itself is a bit more vague, leaving it as > When transitioning back from the user agent code to script, pop the element > queue from the processing stack and invoke callbacks in that queue.
