See https://github.com/whatwg/dom/issues/831 We should prototype this feature.
Created attachment 462555 [details] WIP
Created attachment 462604 [details] WIP2
Created attachment 462605 [details] WIP3
Created attachment 462606 [details] WIP4
Pull request: https://github.com/WebKit/WebKit/pull/4693
Committed 254964@main (46837e56d6f5): <https://commits.webkit.org/254964@main> Reviewed commits have been landed. Closing PR #4693 and removing active labels.
<rdar://problem/100515573>