Metal: Simplify geometry functions translation Check whether a vector or a scalar variant is needed and emit only what is necessary. Reduced the generated MSL for: - atan/atan2 - length - distance - dot - normalize - faceforward - reflect - refract Fixed: angleproject:8487 Fixed: angleproject:8489 Change-Id: I3be39e55997062136aae2782269a65c0c738d6cf Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5217532 Reviewed-by: Geoff Lang <geofflang@chromium.org> Reviewed-by: Kenneth Russell <kbr@chromium.org> Commit-Queue: Alexey Knyazev <lexa.knyazev@gmail.com>