For structures and arrays.
This behaves identically to the per-element zero-initialization, but can be significantly less verbose.
Change-Id: I380ef86f16c2b3f37a9de2820e707f368955b761
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/56764
Auto-Submit: Ben Clayton <bclayton@google.com>
Reviewed-by: David Neto <dneto@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>