Passing dEQP tests requires this check, which seems to be a valid interpretation
of ESSL3 spec section 4.1.9.

BUG=angleproject:941
TEST=dEQP-GLES3.functional.shaders.arrays.invalid.*

Change-Id: Iae88e6bb8e4ec784a2f1c8a94554e1e5c5e3ee85
Reviewed-on: https://chromium-review.googlesource.com/267430Reviewed-by: Zhenyao Mo <zmo@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Olli Etuaho <oetuaho@nvidia.com>