This prevents a spurious D3D runtime warning, which was clogging up
some of our test output.

BUG=angleproject:1660

Change-Id: I1a747ba7532323b989dbed1ee7c78b3b457768a6
Reviewed-on: https://chromium-review.googlesource.com/437724Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>