This is required to handle materialized values, and for constant
expressions.
Bug: tint:1504
Change-Id: If0a49e9b03566c06aa6e4e4c284fc427e1541e91
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/92082
Reviewed-by: Dan Sinclair <dsinclair@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Ben Clayton <bclayton@chromium.org>