This backs out all work from bug 1627075 as well as all of its
descendents. There were a few conflicts when backing this out but
overall it was pretty clean, so I would say it's a fairly mild
level of risk. Historically Nathan Froyd has reviewed these patches,
but he is no longer at Mozilla, and no one else is particularly
familiar with the code, so I am passing this off to RyanVM who has
at least been familiar with the history of the bug.

Differential Revision: https://phabricator.services.mozilla.com/D90096