This patch was originally reverted only because a dependency patch failed a
buggy Chromium test.

This reverts commit aebd002d.

TEST=dEQP-GLES3.functional.shaders.constant_expressions.*
BUG=angleproject:817

Change-Id: Ia5acf15518ea89717c0cfe1398cb18ea27be5b19
Reviewed-on: https://chromium-review.googlesource.com/275811Tested-by: Olli Etuaho <oetuaho@nvidia.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>