Make corelib_strong tests strong-mode compliant

tests/corelib_strong/list_map_test.dart

 // Copyright (c) 2012, 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";
 
 main() {
   testOperations();
 }
 
@@ skipping 38 matching lines @@
   Expect.listEquals(subr,
       reversed.skip(2).toList().reversed.skip(2).toList().reversed.toList());
 
 
   void testList(List list) {
     var throws = const ThrowMarker();
     var mappedList = new List<int>(list.length);
     for (int i = 0; i < list.length; i++) {
       mappedList[i] = rev(list[i]);
     }
-    Iterable reversed = list.map(rev);
+    Iterable<int> reversed = list.map(rev);
 
     void testEquals(v1, v2, path) {
       if (v1 is Iterable) {
         Iterator i1 = v1.iterator;
         Iterator i2 = v2.iterator;
         int index = 0;
         while (i1.moveNext()) {
           Expect.isTrue(i2.moveNext(),
               "Too few actual values. Expected[$index] == ${i1.current}");
           testEquals(i1.current, i2.current, "$path[$index]");
@@ skipping 85 matching lines @@
   testList([0, 1, 2, 3]);
   testList([3, 4, 5, 6]);
   testList([10, 11, 12, 13]);
   testList(l);
   testList(r);
   testList(base);
 
   // Reverse const list.
   Expect.listEquals(r, l.map(rev).toList());
 }