Validate opaque operands against binary operators Add checks that opaque operands can only be used with array indexing and field section, as mentioned in ESSL 3.10 section 4.1.7. BUG=angleproject:2028 Change-Id: I41b7f10785bf712dfc999f85ebff925341c51911 Reviewed-on: https://chromium-review.googlesource.com/497767 Commit-Queue: Olli Etuaho <oetuaho@nvidia.com> Reviewed-by: Olli Etuaho <oetuaho@nvidia.com>