Add websocket files to dummy io.dart implementation for dart2js.

runtime/bin/websocket.dart

 // Copyright (c) 2012, 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.
 
 /**
  * The web socket protocol is implemented by a HTTP server handler
  * which can be instantiated like this:
  *
- * WebSocketHandler wsHandler = new WebSocketHandler();
+ *     WebSocketHandler wsHandler = new WebSocketHandler();

[ahe, 2012/04/27 09:27:45]

Code samples should be wrapped in [:CODE_HERE:].

[Mads Ager (google), 2012/04/27 09:29:50]

Yes, I know. But that will look horrible with the current version of dartdoc. :(

[Bob Nystrom, 2012/04/27 18:06:37]

I think what Mads is doing here is fine. The indentation defines a code block in
markdown. Unlike [: ... :], I think, this also unambiguously lets dartdoc know
that it should be a <pre> code block and not <code>.

  *
  * and then its onRequest method can be assigned to the HTTP server, e.g.
  *
- * server.defaultHandler = wsHandler.onRequest;
+ *     server.defaultHandler = wsHandler.onRequest;
  *
  * or
  *
- * server.addRequestHandler((req) => reg.path == "/ws", wsHandler.onRequest);
- *
+ *     server.addRequestHandler((req) => req.path == "/ws",
+ *                              wsHandler.onRequest);
  */
 interface WebSocketHandler default _WebSocketHandler {
   WebSocketHandler();
 
   /**
    * Request handler to be registered with the HTTP server.
    */
   void onRequest(HttpRequest request, HttpResponse response);
 
   /**
@@ skipping 40 matching lines @@
    */
   close([int status, String reason]);
 }
 
 
 class WebSocketException implements Exception {
   const WebSocketException([String this.message = ""]);
   String toString() => "WebSocketException: $message";
   final String message;
 }