Remove unused code in ProgramPipeline shaderUniforms is set but never used. Bug: b/275102061 Change-Id: Ided52748f6e8925cdbbb996d70966de2d1fc2c9a Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4727743 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Charlie Lao <cclao@google.com> Reviewed-by: Roman Lavrov <romanl@google.com>