The patch adds D3D11 as a testable platform to the multiview performance
tests.

BUG=angleproject:2062
TEST=angle_perftests

Change-Id: I2266073860fd53f546ce9a414bc343b582c77f70
Reviewed-on: https://chromium-review.googlesource.com/645849Reviewed-by: Olli Etuaho <oetuaho@nvidia.com>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>