Fix analyzer redness.

tests/language/override_inheritance_field_test.dart

 // Copyright (c) 2014, 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.
 
 class A {
   get getter1 => null; /// 01: ok
   num get getter2 => null; /// 02: ok
   num get getter3 => null; /// 03: ok
   int get getter4 => null; /// 04: ok
   int get getter5 => null; /// 05: static type warning
@@ skipping 38 matching lines @@
 abstract class I {
   num get getter7 => null; /// 07: continued
   String get getter8 => null; /// 08: continued
   int get getter9 => null; /// 09: static type warning
   int get getter10 => null; /// 10: static type warning
   int get getter11 => null; /// 11: static type warning
   set setter10(num _) => null; /// 30: continued
   set setter11(String _) => null; /// 31: continued
   set setter12(int _) => null; /// 32: static type warning
   set setter13(int _) => null; /// 33: static type warning
+  set setter13(num _) => null; /// 33a: static type warning
   set setter14(int _) => null; /// 34: static type warning
 }
 
 abstract class J {
   String get getter9 => null; /// 09: continued
   num get getter10 => null; /// 10: continued
   num get getter11 => null; /// 11: continued
   set setter12(String _) => null; /// 32: continued
   set setter13(num _) => null; /// 33: continued
+  set setter13(int _) => null; /// 33a: continued
   set setter14(num _) => null; /// 34: continued
 }
 
 abstract class Class extends B implements I, J {
   get getter1 => null; /// 01: continued
   num get getter2 => null; /// 02: continued
   int get getter3 => null; /// 03: continued
   num get getter4 => null; /// 04: continued
   double get getter5 => null; /// 05: continued
   double get getter6 => null; /// 06: continued
@@ skipping 27 matching lines @@
   num field11; /// 51: continued
   num field12; /// 52: continued
   set field13(String _) {} /// 53: continued
   String field14; /// 54: continued
 }
 
 class SubClass extends Class {
   double get getter10 => null; /// 10: continued
   String get getter11 => null; /// 11: continued
   set setter13(double _) => null; /// 33: continued
+  set setter13(double _) => null; /// 33a: continued
   set setter14(String _) => null; /// 34: continued
 }
 
 main() {
   new SubClass();
 }