adds spec data to MIDI interfaces

[rachelandrew]

Adds spec URLs to the MIDI interfaces as I'm creating the documentation pages.

I also removed a duplicate statechange event from MIDIAccess, as this seemed to be a duplicate of onstatechange.

[foolip]

Adds spec URLs to the MIDI interfaces as I'm creating the documentation pages.

Excellent! I can review this.

I also removed a duplicate statechange event from MIDIAccess, as this seemed to be a duplicate of onstatechange.

Unfortunately support of events is a bit of a mess in BCD, with #7545 describing the current state of things with no clear conclusion for how to improve it. We have lots of APIs with both onfoo and foo_event entries, and while I've never asked for foo_event entries to be added, I also don't think we should remove them until that issue has been resolved somehow.

[foolip]

Let's keep this entry. Unfortunately there's nothing to link to in the spec, the "event itself" (as opposed to the onstatechange property) only shows up as that "statechange" string in step 3 of the algorithm in https://webaudio.github.io/web-midi-api/#dom-midiaccess-onstatechange.

[rachelandrew]

I've just re-added that.

[foolip]

Oops, I found another thing.

[foolip]

Thanks @rachelandrew for your patience!