Remove Expect from core library.

tests/corelib/list_reversed_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();
 }
 
 void testOperations() {
   // Comparison lists.
   List l = const [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
   List r = const [10, 9, 8, 7, 6, 5, 4, 3, 2, 1];
   // A base list that starts out like l.
@@ skipping 16 matching lines @@
   Expect.listEquals(subr, reversed.reversed.skip(2).take(6).reversed);
   Expect.listEquals(subr, reversed.reversed.take(8).skip(2).reversed);
   Expect.listEquals(subr, reversed.take(8).reversed.take(6).reversed);
   Expect.listEquals(subr, reversed.reversed.take(8).reversed.take(6));
   Expect.listEquals(subr, reversed.reversed.skip(2).reversed.skip(2));
   Expect.listEquals(subr, reversed.skip(2).reversed.skip(2).reversed);
 
   // Reverse const list.
   Expect.listEquals(r, l.reversed);
 }