Change to HTML: https://github.com/whatwg/html/pull/2530. Change to service workers: https://github.com/w3c/ServiceWorker/pull/1130. Tests: https://github.com/w3c/web-platform-tests/issues/5567. (https://github.com/w3c/web-platform-tests/pull/5003 has more tests as part of SharedArrayBuffer postMessage() integration.)
I'm implementing this in Chromium (see intent to implement here: https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/Z_XzejHJTrs). It would be useful to know if this is on the radar for WebKit.
Search for "messageerror" shows that this isn't implemented yet. It is in EventNames.h, but never fired. Unfortunately, these event handler attributes were added, which might confuse feature detection: https://trac.webkit.org/browser/webkit/trunk/Source/WebCore/workers/service/ServiceWorkerContainer.idl?rev=267935#L49 https://trac.webkit.org/browser/webkit/trunk/Source/WebCore/workers/service/ServiceWorkerGlobalScope.idl?rev=267935#L48
<rdar://problem/96467919>
Pull request: https://github.com/WebKit/WebKit/pull/6654
Committed 256896@main (5e2beb55a112): <https://commits.webkit.org/256896@main> Reviewed commits have been landed. Closing PR #6654 and removing active labels.