swift234

Fix up and re-enable test.

This was disabled after one of the pass pipeline changes resulted in the
test failing only in certain configurations (unoptimized stdlib
build). Previously, the same test had been updated for other pipeline
changes, but the more recent pipeline changes made the previous updates
unnecessary.

This change reverts those previous updates, and adds new updates to deal
with changes that have happened since the test was
disabled (specifically signature optimization firing in some cases where it
wasn't before).