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

tests/standalone/io/secure_stream_test.dart

Index: tests/standalone/io/secure_stream_test.dart
diff --git a/tests/standalone/io/secure_stream_test.dart b/tests/standalone/io/secure_stream_test.dart
index 150932f25aad9a47b0a7ca0e16a1c0fec2ad8231..8d514e6bf4a5016f3b8029454ab68944f843813d 100644
--- a/tests/standalone/io/secure_stream_test.dart
+++ b/tests/standalone/io/secure_stream_test.dart
@@ -12,6 +12,7 @@
 #import("dart:io");
 
 void main() {
+  ReceivePort keepAlive = new ReceivePort();
   SecureSocket.initialize();
   // TODO(3593): Use a Dart HTTPS server for this test.
   // When we use a Dart HTTPS server, allow --short_socket_write. The flag
@@ -30,5 +31,6 @@ void main() {
   input.onClosed = () {
     String fullPage = Strings.concatAll(chunks);
     Expect.isTrue(fullPage.contains('</body></html>'));
+    keepAlive.close();
   };
 }