The newer validation layers picked up this missing bit.

BUG=angleproject:2237

Change-Id: I5bb2f1db3a4e284c003de0f5b23f7f613056af3a
Reviewed-on: https://chromium-review.googlesource.com/760637
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Frank Henigman <fjhenigman@chromium.org>