Existing CONSTANT_COLOR/CONSTANT_ALPHA limitation was generalized to independent blend states with draw call invalidation and a new end2end test. dEQP tests that are incompatible with this limitation result in INVALID_OPERATION and are marked as FAIL.

D3D11 renderer always normalizes and deduplicates requested blend states based on their enabled features and bound framebuffer.

Bug: angleproject:4394
Change-Id: I284796e18be71de1b5bfb087d36f6a45be4c3f70
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2070575
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>