D3D11: Handle multi-view Draw* calls Because the ANGLE_multiview extension uses instancing to multiply geometry for each view, Draw* calls with an active multiview program have to be handled in the follwing way: 1) Convert non-instanced Draw calls to their instanced versions. 2) Multiply the number of instances in an instanced Draw call by the number of views. The patch also applies the viewport offsets to the viewport and scissor rectangle and propagates the computed viewports and scissors to the D3D11 runtime. BUG=angleproject:2062 TEST=angle_end2end_tests Change-Id: I8b4295c95c2cc0c1046c67e1fb1a782a46703292 Reviewed-on: https://chromium-review.googlesource.com/618331 Commit-Queue: Martin Radev <mradev@nvidia.com> Reviewed-by: Jamie Madill <jmadill@chromium.org>