Generate error on program-framebuffer num views mismatch According to the ANGLE_multiview spec Draw* commands should generate an INVALID_OPERATION error if the program uses the multiview extension and the number of views in the active draw framebuffer and active program differs. The patch addresses this by extending the base draw call validation. BUG=angleproject:2062 TEST=angle_end2end_tests Change-Id: I369070beb5ccb17211dbe61ebec40bfcbcf5bc4e Reviewed-on: https://chromium-review.googlesource.com/586605 Commit-Queue: Martin Radev <mradev@nvidia.com> Reviewed-by: Corentin Wallez <cwallez@chromium.org>