The ANGLE_multiview extension can be supported with three possible code
paths - through view being selected in the vertex shader on D3D and
OpenGL, and through the view being selected in the geometry shader on
D3D only. This patch extends the multi-view performance tests to
benchmark these three different code paths.

BUG=angleproject:2062
TEST=angle_end2end_tests

Change-Id: I443e4db64a95eede1142718a43a095ee5a03738c
Reviewed-on: https://chromium-review.googlesource.com/652466
Commit-Queue: Martin Radev <mradev@nvidia.com>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Olli Etuaho <oetuaho@nvidia.com>