Role-specific defaults should be addressed as reflectable in the idl or in normative prose

[joanmarie]

(See issue #1584 for including more explicit language on user agents doing the reflection as shown in the examples.)

The text which is currently in the spec does not take role-specific default values (e.g. aria-orientation on a scrollbar versus aria-orientation on a progressbar).

[cookiecrook]

@rniwa mentioned on Tuesday that several things are now allowed in IDL that weren't a few years ago... There was a previous issue #1058 where reflected string attributes could not be nullable, but that may have changed. Ryosuke, could you summarize your comments about what could/should change wrt the ARIA IDL? Thank you.