Revert "Remove Expect from core library."

tests/language/full_stacktrace3_test.dart

Index: tests/language/full_stacktrace3_test.dart
diff --git a/tests/language/full_stacktrace3_test.dart b/tests/language/full_stacktrace3_test.dart
index 4bacd04624266e4e6d75bf85c76eb0be6a464276..64abc934aafa32bff5385ad7032478db11062ddb 100644
--- a/tests/language/full_stacktrace3_test.dart
+++ b/tests/language/full_stacktrace3_test.dart
@@ -1,9 +1,3 @@
-// (c) 2013, 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";
-
 void func1() {
   throw new Exception("Test peanut gallery request for Full stacktrace");
 }