socket: Add comment about the close() call in _try_to_reconnect()

(imported from commit 87e32adcb9eeb066b6f3ecd85550d00263e0a4e9)

static/js/socket.js

@@ -308,6 +308,9 @@ Socket.prototype = {
         this._is_authenticated = false;
         this._is_reconnecting = true;
         this._reconnect_initiation_time = now;
+        // This is a little weird because we're also called from the SockJS
+        // onclose handler.  Fortunately, close() does nothing on an
+        // already-closed SockJS object.
         this._sockjs.close();
 
         this._reconnect_timeout_id = setTimeout(function () {