Fix include guards.

BUG=angle:733

Change-Id: I08b2c11c4831f1161c178c1842b10e807185aced
Reviewed-on: https://chromium-review.googlesource.com/230831
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>
In Clear11, use ID3D11DeviceContext1::ClearView when appropriate

Change-Id: I81fe722973aa3c89ea03501543ab74d92e26b02b
Reviewed-on: https://chromium-review.googlesource.com/228620
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>