Summary:
Depends on D19284. Ref T13110. It's now possible to get a revision into a "Abandoned + But, Never Promoted From Draft" state. Show this in the header and provide the draft hint above the comment area.
Also, remove `shouldBroadcast()`. The method `getShouldBroadcast()` now has the same meaning.
Finally, migrate existing drafts to `shouldBroadcast = false` and default `shouldBroadcast` to `true`. If we don't do this, every older revision becomes a non-broadcasting revision because this flag was not explicitly set on revision creation before, only on promotion out of draft.
Test Plan: Ran migration; abandoned draft revisions and ended up in a draft + abandoned state.
Subscribers: PHID-OPKG-gm6ozazyms6q6i22gyam
Maniphest Tasks: T13110
Differential Revision: https://secure.phabricator.com/D19285
