Fire the pushsubscriptionchange event in service workers when an origin for which a push subscription existed in the past, but which was revoked because of a permission change (from granted to deny/default), is re-granted notification permission. The event will be fired with an empty oldSubscription and newSubscription.
This change is helpful for web developers and for users. On the one hand, when regranting notification permissions, used are likely to expect to start receiving again notifications right away. On the other hand, web developers must basically keep trying resubscribing to notifications in order to recover from a permission being ungranted and then granted again. The specification supports the pushsubscriptionchange event, although is relatively vague around the exact circumstances in which such event may or should be fired.