[bugfix] Evaluate Newton-polynomias as raw field

If domain and range are FV<k,1,1> and the derivative is FM<k,1,1> the other code fails because these do not interact like scalars would do. Maybe this should be fixed in dune-common. However, since the class only implements univariate polynomials we can simply evaluate the Newton-polynomial using the raw field type and cast to the derivative type later on.