ParseContext: validate additional restriction for the ? and , operators WebGL2 shaders have added restriction to improve portability for some OpenGL compilers that do not support arbitrary ternary and sequence operators. It disallows these operators for arrays, structs containing arrays and the void type. BUG=612066 Change-Id: Id11042051bce25a91e57deaa9591d4d813fed7aa Reviewed-on: https://chromium-review.googlesource.com/359949 Reviewed-by: Olli Etuaho <oetuaho@nvidia.com> Reviewed-by: Corentin Wallez <cwallez@chromium.org> Commit-Queue: Corentin Wallez <cwallez@chromium.org>