Fix hang when opening sockets on ports that are not available.

runtime/bin/socket_impl.dart

 // Copyright (c) 2011, 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.
 
 
 class _SocketBase {
   // Bit flags used when communicating between the eventhandler and
   // dart code. The EVENT flags are used to indicate events of
   // interest when sending a message from dart code to the
   // eventhandler. When receiving a message from the eventhandler the
@@ skipping 183 matching lines @@
   /*
    * Constructor for server socket. First a socket object is allocated
    * in which the native socket is stored. After that _createBind
    * is called which creates a file descriptor and binds the given address
    * and port to the socket. Null is returned if file descriptor creation or
    * bind failed.
    */
   factory _ServerSocket(String bindAddress, int port, int backlog) {
     ServerSocket socket = new _ServerSocket._internal();
     if (!socket._createBindListen(bindAddress, port, backlog)) {
+      socket.close();
       return null;
     }
     if (port != 0) {
       socket._port = port;
     }
     return socket;
   }
 
   _ServerSocket._internal();
 
@@ skipping 26 matching lines @@
   /*
    * Constructor for socket. First a socket object is allocated
    * in which the native socket is stored. After that _createConnect is
    * called which creates a file discriptor and connects to the given
    * host on the given port. Null is returned if file descriptor creation
    * or connect failed.
    */
   factory _Socket(String host, int port) {
     Socket socket = new _Socket._internal();
     if (!socket._createConnect(host, port)) {
+      socket.close();
       return null;
     }
     return socket;
   }
 
   _Socket._internal();
   _Socket._internalInputOnly() : _closedRead = true;
   _Socket._internalOutputOnly() : _closedWrite = true;
 
   int available() {
@@ skipping 87 matching lines @@
     }
     return _outputStream;
   }
 
   bool _closedRead = false;
   bool _closedWrite = false;
   SocketInputStream _inputStream;
   SocketOutputStream _outputStream;
 }