These can be used instead of direct access of the arraySize field in
Chromium, so that arrays of arrays support can be implemented inside
ANGLE without breaking the Chromium build.

BUG=angleproject:2125
TEST=angle_unittests

Change-Id: I123c2a18549e8f6e40ade946870a5437faf2155e
Reviewed-on: https://chromium-review.googlesource.com/718201Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>