Make sure to process WebSocket frames when closing a WebSocket

sdk/lib/io/websocket_impl.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.
 
 part of dart.io;
 
 const String _webSocketGUID = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
 
 // Matches _WebSocketOpcode.
 class _WebSocketMessageType {
@@ skipping 941 matching lines @@
   Future get done => _sink.done;
 
   Future close([int code, String reason]) {
     if (_isReservedStatusCode(code)) {
       throw new WebSocketException("Reserved status code $code");
     }
     if (_outCloseCode == null) {
       _outCloseCode = code;
       _outCloseReason = reason;
     }
-    if (_closeTimer == null && !_controller.isClosed) {
-      // When closing the web-socket, we no longer accept data.
-      _closeTimer = new Timer(const Duration(seconds: 5), () {
-        // Reuse code and reason from the local close.
-        _closeCode = _outCloseCode;
-        _closeReason = _outCloseReason;
-        _subscription.cancel();
-        _controller.close();
-        _webSockets.remove(_serviceId);
-      });
+    if (!_controller.isClosed) {
+      // If a close has not yet been received from the other end then
+      //   1) make sure to listen on the stream so the close frame will be
+      //      processed if received.
+      //   2) set a timer terminate the connection if a close frame is
+      //      not received.
+      if (!_controller.hasListener) {
+        _controller.stream.drain().catchError((_) => {});
+      }
+      if (_closeTimer == null) {
+        // When closing the web-socket, we no longer accept data.
+        _closeTimer = new Timer(const Duration(seconds: 5), () {
+          // Reuse code and reason from the local close.
+          _closeCode = _outCloseCode;
+          _closeReason = _outCloseReason;
+          _subscription.cancel();
+          _controller.close();
+          _webSockets.remove(_serviceId);
+        });
+      }
     }
     return _sink.close();
   }
 
   void _close([int code, String reason]) {
     if (_writeClosed) return;
     if (_outCloseCode == null) {
       _outCloseCode = code;
       _outCloseReason = reason;
     }
@@ skipping 34 matching lines @@
            (code < WebSocketStatus.NORMAL_CLOSURE ||
             code == WebSocketStatus.RESERVED_1004 ||
             code == WebSocketStatus.NO_STATUS_RECEIVED ||
             code == WebSocketStatus.ABNORMAL_CLOSURE ||
             (code > WebSocketStatus.INTERNAL_SERVER_ERROR &&
              code < WebSocketStatus.RESERVED_1015) ||
             (code >= WebSocketStatus.RESERVED_1015 &&
              code < 3000));
   }
 }