Fix HTTP sample implementation to actually wait for connections before attempting to write.

samples/chat/http.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.
 
 #library("http");
 #source("http_impl.dart");
 
 /**
  * HTTP status codes.
  */
@@ skipping 185 matching lines @@
 }
 
 
 /**
  * HTTP client factory.
  */
 interface HTTPClient factory HTTPClientImplementation {
   HTTPClient();
 
   /**
-   * Open a HTTP connection.
+   * Open a HTTP connection. The [openHandler] is called with an
+   * HTTPClientRequest when the connection has been successfully
+   * opened.
    */
-  HTTPClientRequest open(String method, String host, int port, String path);
+  void open(String method, String host, int port, String path);
 
   /**
    * Shutdown the HTTP client releasing all resources.
    */
   void shutdown();
+
+  /**
+   * Set the open handler that is called on successful open operations.
+   */
+  void set openHandler(void handler(HTTPClientRequest request));
 }
 
 
 /**
  * HTTP request for a client connection.
  */
 interface HTTPClientRequest factory HTTPClientRequestImplementation {
   /**
    * Gets and sets the content length of the request. If the size of
    * the request is not known in advance set content length to -1,
@@ skipping 161 matching lines @@
       } else {
         value = queryString.substring(currentPosition, position);
         currentPosition = position + 1;
       }
       result[HTTPUtil.decodeUrlEncodedString(name)] =
         HTTPUtil.decodeUrlEncodedString(value);
     }
     return result;
   }
 }