Refactor and clean up uniform validation. Move uniform value checking to two new functions: ValidateUniformValue() and ValidateUniformMatrixValue(). This reduces code duplication slightly and paves the way for further validation of sampler uniforms in a later change. The checking also becomes slightly more efficient by virtue of reording the tests to put cheap/common cases first. ValidateUniformCommonBase() moves to the anonymous namespace and loses an unused parameter. BUG=angleproject:1711 Change-Id: I6c4deeea27c54027f542500644636064167d5714 Reviewed-on: https://chromium-review.googlesource.com/431677 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org>