Test using the same texture with multiple samplers. This covers a regression introduced with texture dirty bits. BUG=angleproject:1387 Change-Id: Ic8112718c185298ef54ec5a6f6ed2cd519e010d6 Reviewed-on: https://chromium-review.googlesource.com/653586 Reviewed-by: Geoff Lang <geofflang@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>