Add a very basic BidiResolverTest file

Unclear if we should test our UBA via a unittest or via some other
harness, but adding a gtest file in case we go that route.

I expect now that it's easy to gtest this code we'll test more of it.

BUG=242238

Review URL: https://codereview.chromium.org/26709015

git-svn-id: svn://svn.chromium.org/blink/trunk@160374 bbb929c8-8fbe-4397-9dbb-9b2b20218538