Reapply "Implement new model for class members." and "Implement new model for interface members."

tests/compiler/dart2js/lookup_member_test.dart

 // Copyright (c) 2013, 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 subtype_test;
 
 import 'package:expect/expect.dart';
 import "package:async_helper/async_helper.dart";
 import 'type_test_helper.dart';
 import '../../../sdk/lib/_internal/compiler/implementation/dart_types.dart';
@@ skipping 12 matching lines @@
       class B<S> extends A<A<S>> {
         S bar;
       }
       class C<U> extends B<String> with D<B<U>> {
         U baz;
       }
       class D<V> {
         V boz;
       }
       """).then((env) {
-    void expect(DartType receiverType, String memberName,
+    void expect(InterfaceType receiverType, String memberName,
                 DartType expectedType) {
-      Member member = receiverType.lookupMember(memberName);
+      InterfaceTypeMember member = receiverType.lookupMember(memberName);
       Expect.isNotNull(member);
       DartType memberType = member.computeType(env.compiler);
       Expect.equals(expectedType, memberType,
           'Wrong member type for $receiverType.$memberName.');
     }
 
     DartType int_ = env['int'];
     DartType String_ = env['String'];
 
     ClassElement A = env.getElement('A');
@@ skipping 23 matching lines @@
     expect(C_U, 'boz', instantiate(B, [U]));
 
     DartType C_int = instantiate(C, [int_]);
     expect(C_int, 'foo', instantiate(A, [String_]));
     expect(C_int, 'bar', String_);
     expect(C_int, 'baz', int_);
     expect(C_int, 'boz', instantiate(B, [int_]));
   }));
 }