Bug 1348223 removed the cookie viewer/deletion UI from page info. The commit says: Equivalent functionality in a well-maintained interface can be found in the storage manager or the devtools storage inspector. which is not true at all. In particular, the page info UI let me select a subset of cookies for a site and delete those. The devtools storage inspector is readonly, and the storage manager has per-site granularity, not per-cookie. Now that my nightly has updated, I've lost the ability to selectively delete cookies, as far as I can tell.

Go bugzilla, creating a bug and then pretending it didn't....

Looks like the devtools storage inspector _can_ in fact delete cookies. Via a context menu, not keyboard. And you can't select the cookies you want to delete; you have to delete them one at a time. So it's not really usable for what I was using the page info UI for.