Remove Expect from core library.

tests/standalone/io/http_connection_info_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";
 
 void testHttpConnectionInfo() {
   HttpServer server = new HttpServer();
   server.listen("0.0.0.0", 0);
   int clientPort;
   server.defaultRequestHandler = (HttpRequest request, HttpResponse response) {
     Expect.isTrue(request.connectionInfo.remoteHost is String);
     Expect.equals(request.connectionInfo.localPort, server.port);
     Expect.isNotNull(clientPort);
@@ skipping 22 matching lines @@
     };
   };
   conn.onError = (Exception e) {
     Expect.fail("Unexpected error: $e");
   };
 }
 
 void main() {
   testHttpConnectionInfo();
 }