Add a callback to SecureSocket for certificates that fail to be authenticated.

tests/standalone/io/secure_builtin_roots_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";
 import "dart:isolate";
 
 void testGoogleUrl() {
+  ReceivePort keepAlive = new ReceivePort();
   HttpClient client = new HttpClient();
 
   void testUrl(String url) {
     var requestUri = new Uri.fromString(url);
     var conn = client.getUrl(requestUri);
 
     conn.onRequest = (HttpClientRequest request) {
       request.outputStream.close();
     };
     conn.onResponse = (HttpClientResponse response) {
       Expect.isTrue(response.statusCode < 500);
       Expect.isTrue(response.statusCode != 404);
       response.inputStream.onData = () {
         response.inputStream.read();
       };
       response.inputStream.onClosed = () {
         client.shutdown();
+        keepAlive.close();
       };
     };
     conn.onError = (error) => Expect.fail("Unexpected IO error $error");
   }
 
   testUrl('https://www.google.com');
 }
 
 void InitializeSSL() {
   SecureSocket.initialize();
 }
 
 void main() {
   InitializeSSL();
   testGoogleUrl();
 }