Use SV_IsFrontFace to implement gl_FrontFacing on DX11.

TRAC #22426
Signed-off-by: Jamie Madill
Signed-off-by: Daniel Koch
Author: Nicolas Capens

git-svn-id: https://angleproject.googlecode.com/svn/branches/dx11proto@1752 736b8ea6-26fd-11df-bfd4-992fa37f6226
1 file changed