Attempting to fix IE9 XHR cross domain flakiness.

tests/html/html.status

 # Copyright (c) 2013, 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.
 
 async_window_test: Skip #TODO(gram): investigating
 event_test: Skip  # Issue 1996
 interactive_test: Skip # Must be run manually.
 
 [ $compiler == dart2js && $runtime != drt ]
 custom/*: Skip
@@ skipping 138 matching lines @@
 isolates_test: Skip         # BUG(4016)
 localstorage_test: Fail
 microtask_test: Pass, Fail # http://dartbug.com/8300
 postmessage_structured_test: Skip   # BUG(5685): times out.
 serialized_script_value_test: Fail
 url_test: Fail              # IE9 does not support createObjectURL (it is supported in IE10)
 canvasrenderingcontext2d_test/drawImage_video_element: Fail # IE does not support drawImage w/ video element
 canvasrenderingcontext2d_test/drawImage_video_element_dataUrl: Fail # IE does not support drawImage w/ video element
 canvasrenderingcontext2d_test/drawImage_image_element: Pass, Fail # Issue: 11416
 input_element_test/attributes: Fail # IE returns null while others ''
-xhr_cross_origin_test/functional: Pass, Timeout # Issue 12853
 
 # IE9 Feature support statuses-
 # All changes should be accompanied by platform support annotation changes.
 audiobuffersourcenode_test/supported: Fail
 audiocontext_test/supported: Fail
 cache_test/supported: Fail
 crypto_test/supported: Fail
 css_test/supportsPointConversions: Fail
 document_test/supports_cssCanvasContext: Fail
 element_types_test/supported_content: Fail
@@ skipping 201 matching lines @@
 
 [ $compiler == dart2js && $csp && ($runtime == drt || $runtime == safari || $runtime == ff || $runtime == chrome || $runtime == chromeOnAndroid) ]
 # Note: these tests are all injecting scripts by design.  This is not allowed under CSP.
 event_customevent_test: Fail       # Test cannot run under CSP restrictions.
 js_interop_1_test: Skip            # Test cannot run under CSP restrictions (times out).
 js_interop_2_test: Fail, OK        # Test cannot run under CSP restrictions.
 js_interop_3_test: Skip            # Test cannot run under CSP restrictions (times out).
 js_test: Skip                      # Test cannot run under CSP restrictions (times out).
 postmessage_structured_test: Skip  # Test cannot run under CSP restrictions (times out).
 safe_dom_test: Skip                # Test cannot run under CSP restrictions (times out).