If the literal was constructed with an 'f', make sure we print it.
Bug: tint:1504
Change-Id: I6f04e31a166919c07574db56b0a2063ce5b8ca5c
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/91965
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>