Also fixes a bug where we weren't validating duplicating
bindings in the shader, and where dynamic offset validation
could be incorrectly fetching the wrong bindings.
Bug: dawn:354
Change-Id: I93178c34eb4d43119e8b9de5738ae4596e9277cd
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/17240
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Commit-Queue: Austin Eng <enga@chromium.org>