Handle multiview 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. BUG=angleproject:2062 TEST=angle_end2end_tests Change-Id: I19119e8178f70336e5dbb1e5eed0658b5b9f43d7 Reviewed-on: https://chromium-review.googlesource.com/593657 Reviewed-by: Geoff Lang <geofflang@chromium.org> Reviewed-by: Corentin Wallez <cwallez@chromium.org> Commit-Queue: Martin Radev <mradev@nvidia.com>