Only assign 'support-for-ie' if it is not defined already.
Only assign 'support-for-ie' if it is not defined already.

JulianWielga/stylus-less,ecmartinez/nib,tj/nib,rstacruz/nib,ilovezy/nib,seleckis/nib-pushup,F4-Group/nib,ilovezy/nib,seleckis/nib-pushup,tj/nib,F4-Group/nib,ecmartinez/nib