Allow IdPs to return JSON objects rather than Strings back to RPs #13
Description
IdPs can currently return a token which is a USVString through the id assertion endpoint, which, in theory, can actually also contain JSON via JSON.stringify(data).
w3c-fedid/FedCM#572 (comment) suggests that it would be easier for IdPs if they could actually return an object as opposed to a JSON-serialized USVString, which I think can have its merits.