The '%' operator in GLSL is integer-only. Use the full OpFRem
expression: (a - b * trunc(a / b)).
Bug: tint:1270
Change-Id: I0a969983bef132e004ce456d4a738488e400a61b
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/68760
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>