Test multiview extension warning
Test multiview extension warning

Ensure that a warning is generated if the shader tries to set a global
layout qualifier. Since a num_views layout qualifier is the only valid
global layout qualifier in GLSL ES 1.00, it's sufficient that
checkCanUseExtension() that generates the warning is called for
"num_views" specifically. Parsing "layout" or "in" storage qualifier
may use the simpler isExtensionEnabled() check that doesn't generate a
warning.

BUG=angleproject:2238
TEST=angle_unittests

Change-Id: I19caff7be9cb4f53c581b5f5526b7cade08469d6
Reviewed-on: https://chromium-review.googlesource.com/803577
Reviewed-by: Jamie Madill <7e492b4f1c8458024932de3ba475cbf015424c30@chromium.org>
Reviewed-by: Corentin Wallez <470c533e86f4f848c98c7e11fffc2d043494a401@chromium.org>
Commit-Queue: Olli Etuaho <38ae6c0e2772a20e8e989f80cb8c99d274e44242@nvidia.com>

ppy/angle,ppy/angle,ppy/angle,ppy/angle