dart:io | Handle an immediately closed connection in RawSecureServerSocket.

sdk/lib/io/secure_server_socket.dart

Index: sdk/lib/io/secure_server_socket.dart
diff --git a/sdk/lib/io/secure_server_socket.dart b/sdk/lib/io/secure_server_socket.dart
index e9da3c665a4ef7b292415e7d7cae5110250698a7..8ae021eb168752615864556b3fddfe90ad0c53cc 100644
--- a/sdk/lib/io/secure_server_socket.dart
+++ b/sdk/lib/io/secure_server_socket.dart
@@ -212,9 +212,17 @@ class RawSecureServerSocket extends Stream<RawSecureSocket> {
   }
 
   void _onData(RawSocket connection) {
+    var remotePort;
+    try {
+      remotePort = connection.remotePort;
+    } catch (e) {
+      // If connection is already closed, remotePort throws an exception.
+      // Do nothing - connection is closed.
+      return;
+    }
     _RawSecureSocket.connect(
         connection.address,
-        connection.remotePort,
+        remotePort,
         certificateName,
         is_server: true,
         socket: connection,