Currently untestable as nothing currently calls Type(const ast::Type* ty).
Bug: tint:724
Change-Id: I92dd772acd758b0960a7e9a19f15c91414ab505c
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/49527
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>