Integrate multiview state in FBO completeness check The patch extends the FBO completeness validation to include the multiview state members according to the ANGLE_multiview specification. It also changes the numViews in FramebufferAttachment to be consistently of type GLsizei instead of GLint. BUG=angleproject:2062 TEST=angle_end2end_tests Change-Id: Ibe550ba03204d808d96a4edf4807c68421aa1158 Reviewed-on: https://chromium-review.googlesource.com/581193 Commit-Queue: Corentin Wallez <cwallez@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org>