driver(): get rid of PDELab::Native

src/driver.hh

@@ -131,8 +131,7 @@ void driver (const GV& gv, Dune::ParameterTree& ptree)
 
   // Select a linear solver backend
   using LS = PPS::ISTLBackend_SEQ_AMG<
-    Dune::PDELab::Backend::Native<typename GO::Jacobian>,
-    Dune::PDELab::Backend::Native<typename GO::Domain>,
+    typename GO::Jacobian, typename GO::Domain,
     Dune::SeqSSOR, Dune::CGSolver>;
   LS ls(gv.dimension, 100,2);