Revert "Remove Expect from core library."

tests/language/generic_instanceof2_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.
 // Test that instanceof works correctly with type variables.
 
-import "package:expect/expect.dart";
-
 // Test that partially typed generic instances are correctly constructed.
 
 // Test factory case.
 class Foo<K, V> {
   Foo() { }
 
   factory Foo.fac() {
     return new Foo<K, V>();
   }
 
@@ skipping 41 matching lines @@
   Expect.isTrue(moo_raw.MooString() is Moo<int, String>);
 }
 
 
 main() {
   // Repeat type checks so that inlined tests can be tested as well.
   for (int i = 0; i < 5; i++) {
     testAll();
   }
 }