Remove Expect from core library.

tests/standalone/io/web_socket_test.dart

 // Copyright (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.
 //
 // VMOptions=
 // VMOptions=--short_socket_read
 // VMOptions=--short_socket_write
 // VMOptions=--short_socket_read --short_socket_write
 
+import "package:expect/expect.dart";
 import "dart:async";
 import "dart:io";
 import "dart:isolate";
 import "dart:typeddata";
 import "dart:uri";
 
 const String CERT_NAME = 'localhost_cert';
 const String SERVER_ADDRESS = '127.0.0.1';
 const String HOST_NAME = 'localhost';
 
@@ skipping 382 matching lines @@
   SecureSocket.initialize(database: testPkcertDatabase.toNativePath(),
                           password: "dartdart");
 }
 
 
 main() {
   new SecurityConfiguration(secure: false).runTests();
   initializeSSL();
   new SecurityConfiguration(secure: true).runTests();
 }