The recent code cleanup for repositoryform.js introduced a couple of
regressions. One was a typo resulting in an invalid variable name and
incorrect result. There were also a couple of cleanups that resulted in
the wrong variables being shown/hidden.

While here, I fixed up a couple additional style changes, and changed a
parent() selector to parents(), which helps us a bit with the merge to
RBCommons (which needs parents() due to a slightly different page
design).

JSHint passed.
Tested that there weren't any JavaScript errors in the case I hit before

(loading GitHub with multiple hosting service accounts).
Temporary updated GitHub to re-enable the SSH Key Association flag, and

verified that it was shown/hidden appropriately when switching services.