Remove Expect from core library.

tests/standalone/io/secure_server_client_certificate_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";
 import "dart:io";
 import "dart:isolate";
 
 const SERVER_ADDRESS = "127.0.0.1";
 const HOST_NAME = "localhost";
 
 void WriteAndClose(Socket socket, String message) {
   var data = message.charCodes;
   int written = 0;
   void write() {
@@ skipping 101 matching lines @@
   EndTest = () {
     Expect.equals(CLIENT_NAMES.length, server.numConnections);
     server.stop();
     keepAlive.close();
   };
 
   for (var x in CLIENT_NAMES) {
     new SecureTestClient(port, x);
   }
 }