Remove Expect from core library.

tests/standalone/io/web_socket_no_secure_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.
 //
 
 // TODO(7157): Remove this test once the bug is fixed.
 // This is a copy of web_socket_test.dart with the secure connection
 // tests disabled, so it does not crash on Windows.
+import "package:expect/expect.dart";
 import "dart:async";
 import "dart:io";
 import "dart:isolate";
 import "dart:scalarlist";
 import "dart:uri";
 
 const SERVER_ADDRESS = "127.0.0.1";
 const HOST_NAME = "localhost";
 
 
@@ skipping 352 matching lines @@
   var testPkcertDatabase =
       new Path(new Options().script).directoryPath.append("pkcert/");
   SecureSocket.initialize(database: testPkcertDatabase.toNativePath(),
                           password: "dartdart");
 }
 
 
 main() {
   new SecurityConfiguration(secure: false).runTests();
 }