This works around an issue in the GL back-end where the
extended dirty bit wasn't synced in internal blit draw calls.

This bug is preventing progress with the standalone test runner.
This temporarily solution can be put in place until we have
a more complete solution for internal draw state sync.

Bug: angleproject:5160
Change-Id: Id8ae5efa66b249b008a1535b60493c880f5a06a8
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2464824
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>