Adding support for cross-origin requests on IE9.

tools/dom/templates/html/impl/impl_XMLHttpRequest.darttemplate

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of $LIBRARYNAME;
 
 /**
  * A utility for retrieving data from a URL.
  *
  * HttpRequest can be used to obtain data from http, ftp, and file
@@ skipping 203 matching lines @@
    */
   static bool get supportsOverrideMimeType {
 $if DART2JS
     var xhr = new HttpRequest();
     return JS('bool', '("overrideMimeType" in #)', xhr);
 $else
     return true;
 $endif
   }
 
+  /**
+   * Makes a cross-origin request to the specified URL.
+   *
+   * This API provides a subset of [request] which works on IE9. If IE9
+   * cross-origin support is not required then [request] should be used instead.
+   */
+  @Experimental()
+  static Future<String> requestCrossOrigin(String url,
+      {String method, String sendData}) {
+    if (supportsCrossOrigin) {
+      return request(url, method: method, sendData: sendData).then((xhr) {
+        return xhr.responseText;
+      });
+    }
+$if DART2JS
+    var completer = new Completer<String>();
+    if (method == null) {
+      method = 'GET';
+    }
+    var xhr = JS('var', 'new XDomainRequest()');
+    JS('', '#.open(#, #)', xhr, method, url);
+    JS('', '#.onload = #', xhr, convertDartClosureToJS((e) {
+      var response = JS('String', '#.responseText', xhr);
+      completer.complete(response);
+    }, 1));
+    JS('', '#.onerror = #', xhr, convertDartClosureToJS((e) {
+      completer.completeError(e);
+    }, 1));
+
+    if (sendData != null) {
+      JS('', '#.send(#)', xhr, sendData);
+    } else {
+      JS('', '#.send()', xhr);
+    }
+
+    return completer.future;
+$endif
+  }
+
 $!MEMBERS
 }