Revert "Remove Expect from core library."

tests/language/inline_closure_with_constant_arguments_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";
-
 // Test inlining of a closure call with constant propagation.
 primeForSmis(bool b) {
   smi_op(a, b) => a + b;
   if (b) {
     return smi_op(1, 2);
   } else {
     return smi_op(true, false);
   }
 }
 
 
 main() {
   for (var i=0; i<2000; i++) {
     Expect.equals(3, primeForSmis(true));
   }
 }