Make dart:collection strong-mode clean.

tests/corelib/set_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.
 
 library set_test;
 
 
 import 'package:expect/expect.dart';
 import "dart:collection";
 
@@ skipping 505 matching lines @@
   testCESetFrom((x) => new LinkedHashSet<CE>.from(x));
   testCESetFrom((x) => new SplayTreeSet<CE>.from(x));
 
   testCESetFrom((x) => new SplayTreeSet<CE>.from(x,
                                                  customCompare(20), validKey));
   testCESetFrom((x) => new SplayTreeSet<CE>.from(x, identityCompare));
 
   testASetFrom((x) => new Set<A>.from(x));
   testASetFrom((x) => new HashSet<A>.from(x));
   testASetFrom((x) => new LinkedHashSet<A>.from(x));
-  testASetFrom((x) => new SplayTreeSet<A>.from(x));
+  testASetFrom((x) => new SplayTreeSet<A>.from(x, identityCompare));
 }