Currently in the MSL backend we cast int values to uint in order to get
the correct WGSL behaviour for over/under flow. This fails in the case
of host shareable buffers as they use `packed` types which need to get
cast to the non-packed version first.
Bug: tint:1677
Change-Id: I57b70abaa8ca614472a26d63f19c1aef2bd64668
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/103986
Reviewed-by: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Dan Sinclair <dsinclair@chromium.org>
2bcade246a