Fix xfb mode validation with geometry/tessellation In the presence of geometry and/or tessellation shaders, transform feedback mode must match what these shaders produce, instead of what's passed to glDrawArrays. Bug: angleproject:5557 Bug: angleproject:5579 Change-Id: I6a21621e66b31553ed6a3a50c3aebf60e1ac7be5 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2653908 Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Tim Van Patten <timvp@google.com>