Verify occlusion query correctness in a multi-view context The patch adds tests to verify that an occlusion query correctly tracks whether any fragments pass the depth test for any of the views as according to the ANGLE_multiview extension. BUG=angleproject:2062 TEST=angle_end2end_tests Change-Id: Ia85bac4935192554a337c27fad110fbb7f56cf8a Reviewed-on: https://chromium-review.googlesource.com/609961 Commit-Queue: Martin Radev <mradev@nvidia.com> Reviewed-by: Geoff Lang <geofflang@chromium.org>