Depends on D20458. Ref T13276. Although I'm not thrilled about "needCommitPHIDs()", it has a few callers, including custom fields. Allow "need + attach + get" to survive for now since they're reasonably modern, at least.
However, use edges instead of "TABLE_COMMIT" and require need...() + get...(), removing the direct load...().
Also remove RevisionQuery->withCommitPHIDs(...), which has no callers.