This also removes an unused param from the ValidateSPIRV method.
BUG=dawn:543
Change-Id: I369a8097ef49751cedbe6605989750a292027b6b
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/29842
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Ryan Harrison <rharrison@chromium.org>