This matches the terminology that is used throughout the spec.

R=clemensh@chromium.org

Change-Id: I62445e750415e6048b805110c7306f3bdbf9da60
Reviewed-on: https://chromium-review.googlesource.com/c/1408988
Commit-Queue: Ben Titzer <titzer@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58774}