Sync GN unit tests with GYP, add checking script.

Some of these JavaScript gtest tests were missing from the GN build because
they needed to go into a special target.

The included script will find and print out lists of test differences.

Review URL: https://codereview.chromium.org/1289423004

Cr-Original-Commit-Position: refs/heads/master@{#343820}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: b2f72715a4899c690f92529f91fa3a9adf9db5ff
1 file changed
tree: 3baf955d899f684572b858777e062870a8bb0c5e
  1. tools/