Fix warning in standalone in new validation. BUG=angleproject:1512 Change-Id: Ifdb8d4c38e3c90e03eee42ba9fd6390dffd61363 Reviewed-on: https://chromium-review.googlesource.com/388611 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Corentin Wallez <cwallez@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>