Part of the new intrinsic definition parser.
Bug: tint:832
Change-Id: I701072def1a4ca723d10d08b44c1e271b9458212
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/52540
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: David Neto <dneto@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>