Generate an error for active connections when the HTTP client is shutdown

tests/standalone/io/http_redirect_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("dart:io");
 #import("dart:uri");
 
 HttpServer setupServer() {
   HttpServer server = new HttpServer();
@@ skipping 73 matching lines @@
 
 void testManualRedirect() {
   HttpServer server = setupServer();
   HttpClient client = new HttpClient();
 
   int redirectCount = 0;
   HttpClientConnection conn =
      client.getUrl(new Uri.fromString("http://127.0.0.1:${server.port}/1"));
   conn.followRedirects = false;
   conn.onResponse = (HttpClientResponse response) {
-    response.inputStream.onData = () => response.inputStream.read();
+    response.inputStream.onData = response.inputStream.read;
     response.inputStream.onClosed = () {
       redirectCount++;
       if (redirectCount < 10) {
         Expect.isTrue(response.isRedirect);
         checkRedirects(redirectCount, conn);
         conn.redirect();
       } else {
         Expect.equals(HttpStatus.NOT_FOUND, response.statusCode);
         server.close();
         client.shutdown();
@@ skipping 67 matching lines @@
     client.shutdown();
   };
 }
 
 main() {
   testManualRedirect();
   testAutoRedirect();
   testAutoRedirectLimit();
   testRedirectLoop();
 }