This implements the roles, states, and action names, but omits the state change event part that is currently made impossible by us recreating the html:summary accessible once it toggles the html:details open state. This is probably due to some reframing causing us to recreate the accessible. Suggest to move that to a separate bug and implement the basics now and the event later.
MozReview-Commit-ID: FEi5RIXdkG0
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extra : rebase_source : 9b65bc28483238e2339561e6494ccc2884cb7c42
Marco Zehe
Frédéric Wang
Alexander Surkov
Jonathan Wei