Do not generate warnings when noSuchMethod is inherited (issue 24337)

tests/language/override_inheritance_no_such_method_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.
 
 // Test use of @proxy and noSuchMethod in relation to abstract methods in
 // concrete classes.
 
 abstract class A {
   method6(); /// 06: static type warning
   method7(); /// 07: static type warning
@@ skipping 25 matching lines @@
 
   noSuchMethod(_) => null; /// 08: continued
 
   noSuchMethod(_) => null; /// 11: continued
 }
 
 @proxy /// 12: static type warning
 class B {
   method12(); /// 12: continued
 
-  noSuchMethod(_) => null; /// 13: static type warning
+  noSuchMethod(_) => null; /// 13: ok
   method13(); /// 13: continued
 }
 
 class Class2 extends B {
 }
 
 main() {
   new Class1();
   new Class2();
 }