Revert "Remove Expect from core library."

tests/language/call_nonexistent_static_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";
-
 // When attempting to call a nonexistent static method, getter or setter, check
 // that a NoSuchMethodError is thrown.
 
 class C {}
 
 class D {
   get hest => 1;  /// 04: continued
   set hest(val) {}  /// 05: continued
 }
 
@@ skipping 76 matching lines @@
   expectNsme(
     test08  /// 08: continued
   );
   expectNsme(
     test09  /// 09: continued
   );
   expectNsme(
     test10  /// 10: continued
   );
 }