The target can be used in Chromium to get basic cppgc types without
building the actual library.

Bug: chromium:1056170
Change-Id: Idaed19d265c63b2665e34d667903804708411c45
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2532308
Auto-Submit: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Omer Katz <omerkatz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71136}