If eventInterfaceName is not an ASCII case-insensitive match for "event" or for the name of an interface that inherits from the Event interface and is supported by the user agent, throw a "NotSupportedError" and terminate these steps.
Supporting interfaces that don't have init*Event seems useless. I think the spec should have a fixed list of supported interface strings (which would be the same as the interfaces that have init*Event), and let new interfaces throw NotSupportedError.
I support this change.
Any others than Event, UIEvent, and MouseEvent? We could keep listing MutationEvent but it should go away, right?
MutationEvent and MutationNameEvent, yeah, I guess, until it's clear that we can drop them.
(In reply to comment #3)
> MutationEvent and MutationNameEvent,
Except not MutationNameEvent since nobody seems to support it.
(In reply to comment #5)
Does not have initProgressEvent().