SPIRV-Val has tightended up validation around input / output interpolation decorations.
This change ensures that the parser and writer do the right thing.
Change-Id: I29c97fdcc48c62aa77b106c42e64fbc54204d607
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/96020
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>