RenderstateCache and Clear11 Optimizations - Unify DepthStencilState and BlendState caches in RenderStateCache with those in Clear11. This will increase cache hit rate and reduce memory usage. - Apply DepthStencilState and BlendState only when required to reduce state sets. BUG=angleproject:1632 Change-Id: I244e3ba189f82814638fa90e2617aa5441024d0f Reviewed-on: https://chromium-review.googlesource.com/453888 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>