This helps take advantage of the GN feature where when a directory is
used as a target name, like //foo/bar/baz, the //foo/bar/baz:baz target
is used automatically.
Bug: chromium:1064305
Change-Id: I2e2d9f308fda1b811482026962ab0770ac45e988
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/18862
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>