Remove Expect from core library.

tests/corelib/list_index_of_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 ListIndexOfTest {
   static testMain() {
     test(new List<int>.fixedLength(5));
     var l = new List<int>();
     l.length = 5;
     test(l);
   }
 
   static void test(List<int> list) {
     list[0] = 1;
@@ skipping 15 matching lines @@
 
     Expect.equals(-1, list.lastIndexOf(4, 2));
     Expect.equals(-1, list.lastIndexOf(4, -5));
     Expect.equals(3, list.lastIndexOf(4, 50));
   }
 }
 
 main() {
   ListIndexOfTest.testMain();
 }