This allows for a more optimal way to filter the result of To(). Updated
Type query functions to make use of it. Added tests.
Change-Id: If3a65259345fbe6b92c6d367ab01fa718bb7cfee
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/44463
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Antonio Maiorano <amaiorano@google.com>