Remove files that have already been ported or do not need to be ported.

client/html/src/WebSocket.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.
-
-interface WebSocket extends EventTarget {
-
-  static final int CLOSED = 3;
-
-  static final int CLOSING = 2;
-
-  static final int CONNECTING = 0;
-
-  static final int OPEN = 1;
-
-  String get URL();
-
-  String get binaryType();
-
-  void set binaryType(String value);
-
-  int get bufferedAmount();
-
-  EventListener get onclose();
-
-  void set onclose(EventListener value);
-
-  EventListener get onerror();
-
-  void set onerror(EventListener value);
-
-  EventListener get onmessage();
-
-  void set onmessage(EventListener value);
-
-  EventListener get onopen();
-
-  void set onopen(EventListener value);
-
-  String get protocol();
-
-  int get readyState();
-
-  void close();
-
-  bool send(String data);
-}