Add specs for API method to allow self-revokation of a permission

As a convience, a dapp may want to allow their users easy (e.g. single click) revocation of permissions that have been granted to themselves. We can expose an API that just allows the dapp to remove any permissions it has been granted.

No file, test, or entry point is named. Start by reviewing the existing permission API specifications and determine the intended self-revocation contract; done means the API method is specified and covered by the relevant specs.

Written by the indexing model from the issue text.