make new optional

Author: James Halliday

lib/sockjs.js

@@ -7,6 +7,11 @@
  */
 
 var SockJS = function(url, dep_protocols_whitelist, options) {
+    if (this === window) {
+        // makes `new` optional
+        return new SockJS(url, dep_protocols_whitelist, options);
+    }
+    
     var that = this, protocols_whitelist;
     that._options = {devel: false, debug: false, protocols_whitelist: [],
                      info: undefined, rtt: undefined};