Bug 1098082 - Follow-up: fix bustage from ckitching not running tests.
Bug 1098082 - Follow-up: unify with fx-team. r=trival
No bug - Roll back overzealous rewrites. r=trivial

This code ships and is used; we can't avoid it.  We could override the
v9 API (apply) but we can't override the v10 API ({get,put}StringSet)
so let's not bother with either.