Use dirty bit for draw indirect buffer Bug: angleproject:1595 Change-Id: I031beab818daca8a20726d7bff564649feefc1f3 Reviewed-on: https://chromium-review.googlesource.com/844214 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>