Re: [whatwg/dom] Add window.event, event.srcElement, event.returnValue as a legacy compat requirements (#407)

@hsivonen I had another look and while I thought I only had nits, I think one problem with `window.event` is that "If event's target's root is not a shadow root" is a runtime check, while this should be based on information known prior to dispatch. And perhaps we should also hide the event if any of its relatedTarget or touch target list contain shadow tree entries, but only while calling listeners in the shadow tree. (See also #585.)

`returnValue` should be safe to implement though and `srcElement` is already in Nightly.

-- 
You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub:
https://github.com/whatwg/dom/pull/407#issuecomment-376461658