[ADT] Don't use a fixture just to get a nonce type for this unittest.

Instead, actually produce a nonce type in the test and use that. This
makes the test, IMO, both simpler and more clear.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@256518 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed