These are expressions, and not specific to `var`s.
Break the tests up into finer granularity.
Bug: tint:656
Change-Id: I6873407127871dfaec55d90f02e0490eef929a30
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/56071
Commit-Queue: Ben Clayton <bclayton@google.com>
Auto-Submit: Ben Clayton <bclayton@google.com>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>