Remove Expect from core library.

tests/standalone/io/http_redirect_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:io";
 import "dart:uri";
 
 HttpServer setupServer() {
   HttpServer server = new HttpServer();
   server.listen("127.0.0.1", 0, backlog: 5);
 
   void addRedirectHandler(int number, int statusCode) {
     server.addRequestHandler(
        (HttpRequest request) => request.path == "/$number",
@@ skipping 339 matching lines @@
 main() {
   testManualRedirect();
   testManualRedirectWithHeaders();
   testAutoRedirect();
   testAutoRedirectWithHeaders();
   testAutoRedirect301POST();
   testAutoRedirect303POST();
   testAutoRedirectLimit();
   testRedirectLoop();
 }