More SSBO related deqp cases pass due to the implementation of atomic
counter.

Bug: angleproject:1951

Change-Id: I1a6ed6001b9b2d06e74aab105d1a7852abbb9902
Reviewed-on: https://chromium-review.googlesource.com/c/1476950Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jiajia Qin <jiajia.qin@intel.com>