Fixed ssbo end2end tests failure The array stride is implementation-dependent if the storage layout is not standard layout. So this change will use std140 as the layout to fix the bug. BUG=767240,angleproject:2255 Change-Id: I21de52ebad6d27783eeade63d6fac81c0842085d Reviewed-on: https://chromium-review.googlesource.com/861313 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>