Remove obsolete TODOs from tests.

tests/corelib/for_in_test.dart

 // Copyright (c) 2011, 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.
 
 import "package:expect/expect.dart";
 
 class ForInTest {
   static testMain() {
     testSimple();
     testBreak();
@@ skipping 35 matching lines @@
     }
     Expect.equals(7, count);
 
     count = 0;
     int i = 0;
     Expect.equals(false, set.contains(i));  // Used to test [i] after loop.
     for (i in set) {
       count += i;
     }
     Expect.equals(7, count);
-    // TODO(ngeoffray): We should really test that [i] is 4 with a set
-    // that preserves order. For now, making sure [i] is in the set
-    // will have to do.
     Expect.equals(true, set.contains(i));
+    // The default implementation of [Set] preserves order.
+    Expect.equals(4, i);
   }
 
   static void testBreak() {
     Set<int> set = getSmallSet();
     int count = 0;
     for (final i in set) {
       if (i == 4) break;
       count += i;
     }
     Expect.equals(true, count < 4);
@@ skipping 18 matching lines @@
     }
 
     Expect.equals(index, set.length);
     Expect.equals(7, closures[0]() + closures[1]() + closures[2]());
   }
 }
 
 main() {
   ForInTest.testMain();
 }