Based on feedback from Al Patrick, Nicolas Capens and Daniel Koch, removed the restriction about draw buffer 0 having to be non-NULL if any higher draw buffers are non-NULL. Appears this can be supported with a NULL FOURCC render target. Removed issue and adjusted introductory text. Review URL: https://codereview.appspot.com/6725048 git-svn-id: https://angleproject.googlecode.com/svn/trunk@1292 736b8ea6-26fd-11df-bfd4-992fa37f6226