Relaxed MessagePort.postMessage

[nikneym]

Removes error return in postMessage, we still missing the implementation for transfer & options but function seem to work for other cases.

[krichprollsch]

What about checking if transfer is given to return error only in this case?
I think it's easier to have an error (+log) knowing we don't support something.

[karlseguin]

We think this is for transfer an object to a different JS context. A frame (what I saw) or a web worker.

If the script does:

port.postMessage(null, [object_to_transfer]);
// we should continue to execute code

I don't think it's worth stopping execution (at that point anyways) because the "transfer" to a frame/webworker failed.