This is to avoid name conflicts once we move all classes from namespace
`type` to `sem`.
Bug: tint:724
Change-Id: I23cdec636cb5bcf0bbba03ee7bb7c44252ddade7
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/48361
Commit-Queue: Antonio Maiorano <amaiorano@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>