Make SamplerState a contained class. This will more easily allow us to use a cached completeness comparison value. The cached value only gets updated on certain setters. Bug: angleproject:2763 Change-Id: Ib80db8517560617087ae8360f7af69d6c2392b76 Reviewed-on: https://chromium-review.googlesource.com/1171507 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Frank Henigman <fjhenigman@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>