Fix some issues after introducing NamedType.

lib/type_algebra.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 library kernel.type_algebra;
 
 import 'ast.dart';
 
 /// Returns a type where all occurrences of the given type parameters have been
 /// replaced with the corresponding types.
 ///
@@ skipping 623 matching lines @@
 
   bool visitTypeParameterType(TypeParameterType node) {
     return variables == null || variables.contains(node.parameter);
   }
 
   bool handleTypeParameter(TypeParameter node) {
     assert(!variables.contains(node));
     return node.bound.accept(this);
   }
 }
-
-Map<dynamic/*=K*/, dynamic/*=W*/ > _mapValues/*<K,V,W>*/(
-    Map<dynamic/*=K*/, dynamic/*=V*/ > map, dynamic/*=W*/ fn(dynamic/*=V*/)) {
-  Map<dynamic/*=K*/, dynamic/*=W*/ > result = {};
-  map.forEach((key, value) {
-    result[key] = fn(value);
-  });
-  return result;
-}