The patch adds support for the three remaining memory qualifiers:
volatile, coherent and restrict.

BUG=angleproject:1442

TEST=angle_unittests
TEST=angle_end2end_tests

Change-Id: Ie662d304af2399468df1d976e04c38dada1e2cec
Reviewed-on: https://chromium-review.googlesource.com/385876
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>