Remove Slip thinko
Remove Slip thinko

The source iterator may produce Slips, but they will be passed as
such to the block, so we shouldn't be checking for this here.

tbrowder/rakudo,rakudo/rakudo,rakudo/rakudo,labster/rakudo,tbrowder/rakudo,tbrowder/rakudo,labster/rakudo,rakudo/rakudo,labster/rakudo,labster/rakudo,salortiz/rakudo,MasterDuke17/rakudo,rakudo/rakudo,labster/rakudo,tbrowder/rakudo,rakudo/rakudo,MasterDuke17/rakudo,MasterDuke17/rakudo,labster/rakudo,tbrowder/rakudo,MasterDuke17/rakudo,salortiz/rakudo,rakudo/rakudo,MasterDuke17/rakudo,salortiz/rakudo,tbrowder/rakudo,MasterDuke17/rakudo,salortiz/rakudo,salortiz/rakudo,salortiz/rakudo