Make corelib_strong tests strong-mode compliant

tests/corelib_strong/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 351 matching lines @@
 // Objects that are equal based on data.
 class CE implements Comparable<CE> {
   final int id;
   const CE(this.id);
   int get hashCode => id;
   bool operator==(Object other) => other is CE && id == (other as CE).id;
   int compareTo(CE other) => id - other.id;
   String toString() => "CE($id)";
 }
 
+typedef int CECompare(CE e1, CE e2);
 // Equality of Id objects based on id modulo value.
 Function customEq(int mod) => (CE e1, CE e2) => ((e1.id - e2.id) % mod) == 0;
 Function customHash(int mod) => (CE e) => e.id % mod;
-Function customCompare(int mod) => (CE e1, CE e2) =>
+CECompare customCompare(int mod) => (CE e1, CE e2) =>
     (e1.id % mod) - (e2.id % mod);
 bool validKey(Object o) => o is CE;
 final customId = new Map.identity();
 int counter = 0;
 int identityCompare(e1, e2) {
   if (identical(e1, e2)) return 0;
   int i1 = customId.putIfAbsent(e1, () => ++counter);
   int i2 = customId.putIfAbsent(e2, () => ++counter);
   return i1 - i2;
 }
@@ skipping 132 matching lines @@
 
   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, identityCompare));
 }