[bindings] Remove custom binding usage from XMLHttpRequest.open()

Source/core/xmlhttprequest/XMLHttpRequest.idl

 /*
  * Copyright (C) 2008, 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 40 matching lines @@
     const unsigned short OPENED = 1;
     const unsigned short HEADERS_RECEIVED = 2;
     const unsigned short LOADING = 3;
     const unsigned short DONE = 4;
 
     [RaisesException=Setter] attribute unsigned long timeout;
     readonly attribute unsigned short readyState;
 
     [RaisesException=Setter] attribute boolean withCredentials;
 
-    [Custom, RaisesException] void open(DOMString method, DOMString url, optional boolean async, optional DOMString user, optional DOMString password);
+    [RaisesException] void open(DOMString method, DOMString url, optional boolean async, [TreatUndefinedAs=NullString] optional DOMString? user, [TreatUndefinedAs=NullString] optional DOMString? password);

[yhirano, 2015/03/24 10:49:39]

TreatNullAs=NullString needed?
Can we have tests?

[Jens Widell, 2015/03/24 13:44:26]

'DOMString?', used here, has the same effect as [TreatNullAs=NullString].

 
     [RaisesException] void setRequestHeader(DOMString header, DOMString value);
 
     [RaisesException] void send(optional (ArrayBuffer or ArrayBufferView or Blob or Document or DOMString or FormData)? data);
 
     void abort();
 
     readonly attribute XMLHttpRequestUpload upload;
 
     // response
     [TreatReturnedNullStringAs=Undefined] DOMString getAllResponseHeaders();
     DOMString? getResponseHeader(DOMString header);
     [Custom=Getter, RaisesException=Getter] readonly attribute DOMString? responseText;
     [RaisesException=Getter] readonly attribute Document responseXML;
 
     [RaisesException=Setter] attribute XMLHttpRequestResponseType responseType;
     [Custom=Getter, RaisesException=Getter] readonly attribute object response;
     readonly attribute DOMString responseURL;
 
     readonly attribute unsigned short status;
     readonly attribute DOMString statusText;
 
     // Extension
     [RaisesException] void overrideMimeType(DOMString override);
 };