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>
