No-op draw calls with rendering feedback loops. This is quite within spec and protects our various back-ends from FB loops. Also makes the check more cached for optimization purposes. Bug: angleproject:4490 Change-Id: Ia82ec88244d07670d68ce53495b5893b8a75ac42 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2118153 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Cody Northrop <cnorthrop@google.com>