Support DOMString[] and regenerate from IDL

client/dom/generated/src/frog/XMLHttpRequest.dart

 
 class XMLHttpRequest native "XMLHttpRequest" {
 
   bool asBlob;
 
   EventListener onabort;
 
   EventListener onerror;
 
   EventListener onload;
@@ skipping 25 matching lines @@
   void abort() native;
 
   void addEventListener(String type, EventListener listener, [bool useCapture = null]) native;
 
   bool dispatchEvent(Event evt) native;
 
   String getAllResponseHeaders() native;
 
   String getResponseHeader(String header) native;
 
-  void open(String method, String url, bool async, [String user = null, String password = null]) native;
+  void open(String method, String url, [bool async = null, String user = null, String password = null]) native;
 
   void overrideMimeType(String override) native;
 
   void removeEventListener(String type, EventListener listener, [bool useCapture = null]) native;
 
   void send([var data = null]) native;
 
   void setRequestHeader(String header, String value) native;
 
   var dartObjectLocalStorage;
 
   String get typeName() native;
 }