Remove Expect from core library.

tests/compiler/dart2js_extra/optional_parameter_test.dart

Index: tests/compiler/dart2js_extra/optional_parameter_test.dart
diff --git a/tests/compiler/dart2js_extra/optional_parameter_test.dart b/tests/compiler/dart2js_extra/optional_parameter_test.dart
index 4fd5ac8ae9a76ca1a720d8360bee470ce4dfdc3b..bb9ac6f2f7fef873e2814c86fe9f52b6b9926008 100644
--- a/tests/compiler/dart2js_extra/optional_parameter_test.dart
+++ b/tests/compiler/dart2js_extra/optional_parameter_test.dart
@@ -2,6 +2,8 @@
 // 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";
+
 class A {
   foo([a]) {
     return a;