First parameter to MessagePort / DedicatedWorkerGlobalScope.postMessage() should be mandatory

[Chris Dumez]

First parameter to MessagePort / DedicatedWorkerGlobalScope.postMessage() should be mandatory:
- https://html.spec.whatwg.org/multipage/comms.html#messageport
- https://html.spec.whatwg.org/multipage/workers.html#dedicated-workers-and-the-dedicatedworkerglobalscope-interface

Currently, WebKit send a bogus MessageEvent whose data attribute is undefined. This causes a testharness error when running the following W3C test:
http://w3c-test.org/workers/interfaces.worker

[Chris Dumez]

Firefox and Chrome already behave this way.

Also note that we already throw when calling window.postMessage() without parameter.

[Chris Dumez]

Created attachment 280841 [details]
Patch

[Geoffrey Garen]

Comment on attachment 280841 [details]
Patch

r=me

[WebKit Commit Bot]

Comment on attachment 280841 [details]
Patch

Clearing flags on attachment: 280841

Committed r201835: <http://trac.webkit.org/changeset/201835>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

[Darin Adler]

Comment on attachment 280841 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=280841&action=review

> Source/WebCore/bindings/js/JSMessagePortCustom.h:54
> +        if (UNLIKELY(state.argumentCount() < 1))
> +            return state.vm().throwException(&state, createNotEnoughArgumentsError(&state));

What is correct behavior when there is one argument but it is undefined? I’d like to see test coverage for that case.