https://github.com/gpuweb/gpuweb/pull/1945 changes the SPIR-V mapping of this operator so that it now maps to OpFRem instead of OpFMod. Polyfill OpFMod with `x - y * floor(x / y)`
Also map the MSL output of this operator to use `fmod()`.
Behavior of this operator is now consistent across all backends.
Fixed: tint:945
Fixed: tint:977
Fixed: tint:1010
Change-Id: Iefa009b905989c55ace24e073ab0e261c7cf69b0
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/58393
Auto-Submit: Ben Clayton <bclayton@google.com>
Commit-Queue: Ben Clayton <bclayton@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: David Neto <dneto@google.com>