Comment 1 for bug 1408109

Given that this feature has no tests, has never been completed and AFAICT is not used by any application, I wonder whether we should just remove this API (but keeping a dummy WebContext.storageAccessPermissionDelegate property). I don't want to leave a half-completed feature around, I don't think it's worth spending time on finishing this, and it's going to make the implementation of site-settings more complicated (as well as being superseded by that)