The test was supposed to use a CF type, but it wasn't updated
for the switch from a naming convention to an attribute. This
restores the original intent (and unfortunately slides all the
offsets).
The code goes into its own sub-tree under 'tools' but tests go under 'test',
so that running 'check-swift' will also run all the SourceKit tests.
SourceKit is disabled on non-darwin platforms.
