We're not supporting these, even as hex-floats. Replace them with finite
float values.
Bug: tint:1504
Change-Id: Id5e304d2bdd79576b68b43a1afb5cce2cd6ad01a
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/91967
Reviewed-by: James Price <jrprice@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>