Should "If target's root is a shadow root, then set event’s target attribute and event’s relatedTarget to null. " be based on the path before dispatch

[smaug----]

.

[annevk]

This was initially added for #511 by @TakayoshiKochi.

If we move target out of a shadow tree, relatedTarget would still leak, so yeah, we should probably change the logic here.

I also think my logic in #513 (comment) was wrong with respect to relatedTarget not able to leak something. If you dispatch a synthetic event and set relatedTarget yourself you would be able to leak something. It's a little unclear if we should guard against that, but it seems reasonable?

Another problem here is that we don't reset anything for touch events. I'm not sure how to address them.

@whatwg/components

[annevk]

To be clear, #585 is the PR for this, which builds on #584 which provides better infrastructure for touch events.