The HLSL writer doesn't really care much for ast::Types, so most of the work here is repointing the logic to fetch the resolved, semantic type.
Output for aliases has changed, as the semantic type resolves away aliases.
Bug: tint:724
Change-Id: I6eb9d5c2fbcd62eef0f9dd145360714db649e13f
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/49530
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>