Ben Clayton 8fca34546b ast: Add PhonyExpression
Represents the `_` in a phony assignment `_ = <expr>`

Bug: tint:1213
Change-Id: Ifb070277b7872aa5ae405e467e28191e625c4c5a
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/67062
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: David Neto <dneto@google.com>
Reviewed-by: James Price <jrprice@google.com>
2021-10-21 18:33:14 +00:00
..
2021-10-21 18:33:14 +00:00