Fix crash in raw_secure_server_socket_test.

runtime/bin/socket_patch.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.
 
 patch class RawServerSocket {
   /* patch */ static Future<RawServerSocket> bind(address,
                                                   int port,
                                                   {int backlog: 0,
                                                    bool v6Only: false}) {
     return _RawServerSocket.bind(address, port, backlog, v6Only);
@@ skipping 806 matching lines @@
               // events, and thus reporting of this error.
               available = 1;
             }
             issueReadEvent();
             continue;
           }
         }
 
         var handler = eventHandlers[i];
         if (i == DESTROYED_EVENT) {
+          assert(isClosing);
           assert(!isClosed);
           isClosed = true;
           closeCompleter.complete();
           disconnectFromEventHandler();
           if (handler != null) handler();
           continue;
         }
 
         if (i == ERROR_EVENT) {
           if (!isClosing) {
@@ skipping 29 matching lines @@
     eventHandlers[ERROR_EVENT] = error;
     eventHandlers[CLOSED_EVENT] = closed;
     eventHandlers[DESTROYED_EVENT] = destroyed;
   }
 
   void setListening({read: true, write: true}) {
     sendReadEvents = read;
     sendWriteEvents = write;
     if (read) issueReadEvent();
     if (write) issueWriteEvent();
-    if (eventPort == null) {
+    if (eventPort == null && !isClosing) {
       int flags = typeFlags & TYPE_TYPE_MASK;
       if (!isClosedRead) flags |= 1 << READ_EVENT;
       if (!isClosedWrite) flags |= 1 << WRITE_EVENT;
       sendToEventHandler(flags);
     }
   }
 
   Future close() {
     if (!isClosing && !isClosed) {
       sendToEventHandler(1 << CLOSE_COMMAND);
@@ skipping 42 matching lines @@
     }
   }
 
   void sendToEventHandler(int data) {
     assert(!isClosing);
     connectToEventHandler();
     _EventHandler._sendData(this, eventPort, data);
   }
 
   void connectToEventHandler() {
+    assert(!isClosed);
     if (eventPort == null) {
       eventPort = new RawReceivePort(multiplex);
       _SocketsObservatory.add(this);
     }
   }
 
   void disconnectFromEventHandler() {
     assert(eventPort != null);
     eventPort.close();
     eventPort = null;
@@ skipping 844 matching lines @@
                        String address,
                        List<int> in_addr,
                        int port) {
   return new Datagram(
       data,
       new _InternetAddress(address, null, in_addr),
       port);
 }
 
 String _socketsStats() => _SocketsObservatory.toJSON();