Fix a Socket edge-case where the socket is closed by peer right after accept, where we havn't set a…

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 472 matching lines @@
         // Don't call the in handler if there is no data available
         // after all.
         if (i == READ_EVENT &&
             typeFlags != TYPE_LISTENING_SOCKET &&
             available() == 0) {
           continue;
         }
         if (i == ERROR_EVENT) {
           reportError(nativeGetError(), "");
         } else if (!isClosed) {
-          handler();
+          // If the connection is closed right after it's accepted, there's a
+          // chance the close-handler is not set.
+          if (handler != null) handler();
         }
       }
     }
     if (isClosedRead && isClosedWrite) close();
     canActivateEvents = true;
     activateHandlers();
   }
 
   void setHandlers({read, write, error, closed, destroyed}) {
     eventHandlers[READ_EVENT] = read;
@@ skipping 714 matching lines @@
     if (_detachReady != null) {
       _detachReady.complete(null);
     } else {
       if (_raw != null) {
         _raw.shutdown(SocketDirection.SEND);
         _disableWriteEvent();
       }
     }
   }
 }