Validating draw buffers now also considers color mask settings It will always return true if all 4 channels of color mask are set to false. This should only apply to WebGL. Will fix this in a later patch. Bug: chromium:958374 Change-Id: I46befaf3ae1b63027dfbb309ac32724c616025d3 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1594629 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org>