And add tests.
This is useful for other tooling.
Change-Id: Ia399071baf6d4bb617f3c73e4ccd4ed72d522c2e
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/111020
Commit-Queue: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>