xhr multipart patch

xhr-multipart.patch

     XHRMultipart.prototype._get = function(){
         var self = this;
         this._xhr = this._request('', 'GET', true);
-        this._xhr.onreadystatechange = function(){
-            if (self._xhr.readyState == 3) self._onData(self._xhr.responseText);
-        };
+        if ("onload" in this._xhr) {
+            this._xhr.onload = function() {
+                self._onData(self._xhr.responseText);
+            }
+        } else {
+            this._xhr.onreadystatechange = function(){
+                if (self._xhr.readyState == 3) self._onData(self._xhr.responseText);
+            };
+        }
         this._xhr.send(null);
     };