Adding support for cross-origin requests on IE9.

tests/html/xhr_cross_origin_test.dart

 // 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.
 
 library XHRCrossOriginTest;
 import '../../pkg/unittest/lib/unittest.dart';
 import '../../pkg/unittest/lib/html_individual_config.dart';
 import 'dart:html';
 import 'dart:json' as json;
 
@@ skipping 38 matching lines @@
       }).catchError((error) {}, test: (error) {
         gotError = true;
         // Consume errors when not supporting cross origin.
         return !HttpRequest.supportsCrossOrigin;
       }).whenComplete(() {
         // Expect that we got an error when cross origin is not supported.
         expect(gotError, !HttpRequest.supportsCrossOrigin);
       });
     });
 
+    test('XHR.requestCrossOrigin', () {
+      var url = '$host/root_dart/tests/html/xhr_cross_origin_data.txt';
+      return HttpRequest.requestCrossOrigin(url).then((response) {
+        expect(response, contains('feed'));
+      });
+    });
+
+    test('XHR.requestCrossOrigin errors', () {
+      var gotError = false;
+      return HttpRequest.requestCrossOrigin('does_not_exist').then((response) {
+        expect(true, isFalse, reason: '404s should fail request.');
+      }).catchError((error) {}, test: (error) {
+        gotError = true;
+        return true;
+      }).whenComplete(() {
+        expect(gotError, isTrue);
+      });
+    });
+
     // Skip the rest if not supported.
     if (!HttpRequest.supportsCrossOrigin) {
       return;
     }
 
     test('XHR Cross-domain', () {
       var url =  '$host/root_dart/tests/html/xhr_cross_origin_data.txt';
       var xhr = new HttpRequest();
       xhr.open('GET', url, async: true);
       var validate = expectAsync1((data) {
@@ skipping 15 matching lines @@
       var url = '$host/root_dart/tests/html/xhr_cross_origin_data.txt';
       return HttpRequest.request(url, withCredentials: true).then((xhr) {
         var data = json.parse(xhr.response);
         expect(data, contains('feed'));
         expect(data['feed'], contains('entry'));
         expect(data, isMap);
       });
     });
   });
 }