Don't wait for websocket closes on failure

RFB._fail() can be called at any time in any state, it is not certain
that we will get a close event on the socket since the socket might not
be open. This caused us to hit the disconnect timeout in such cases.

Fixes issue #678

core/rfb.js

@@ -572,7 +572,11 @@
                     break;
             }
             this._rfb_disconnect_reason = msg;
+
+            // Transition to disconnected without waiting for socket to close
             this._updateConnectionState('disconnecting');
+            this._updateConnectionState('disconnected');
+
             return false;
         },