Remove Expect from core library.

tests/standalone/io/web_socket_protocol_processor_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.
 
+import "package:expect/expect.dart";
 import "dart:math";
 
 part "../../../sdk/lib/io/websocket.dart";
 part "../../../sdk/lib/io/websocket_impl.dart";
 
 class WebSocketFrame {
   WebSocketFrame(int opcode, List<int> data);
 }
 
 // Class that when hooked up to the web socket protocol processor will
@@ skipping 198 matching lines @@
   runTest(65534, 65537, 1);
   print("Fragment messages test, messages $messageCount, frames $frameCount");
   Expect.equals(messageCount, mc.messageCount);
   Expect.equals(0, mc.closeCount);
 }
 
 void main() {
   testFullMessages();
   testFragmentedMessages();
 }