Migrate test-semaphore to base-unittests.

TEST=base-unittests
BUG=v8:3489
LOG=n
R=machenbach@chromium.org

Review URL: https://codereview.chromium.org/494343002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23296 ce2b1a6d-e550-0410-aec6-3dcde31c8c00