Fixing overrideMimeType on IE10.

tools/dom/scripts/dartmetadata.py

 #!/usr/bin/python
 # 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.
 
 """This module provides shared functionality to provide Dart metadata for
 DOM APIs.
 """
 
 import copy
@@ skipping 365 matching lines @@
   'SVGForeignObjectElement': _no_ie_annotations,
   'SVGSetElement': _no_ie_annotations,
   'SQLTransaction': _web_sql_annotations,
   'SQLTransactionSync': _web_sql_annotations,
   'WebGLRenderingContext': _webgl_annotations,
   'WebKitCSSMatrix': _webkit_experimental_annotations,
   'WebSocket': _all_but_ie9_annotations,
   'Worker': _all_but_ie9_annotations,
   'XMLHttpRequest.onloadend': _all_but_ie9_annotations,
   'XMLHttpRequest.onprogress': _all_but_ie9_annotations,
+  'XMLHttpRequest.overrideMimeType': _no_ie_annotations,
   'XMLHttpRequest.response': _all_but_ie9_annotations,
   'XMLHttpRequestProgressEvent': _webkit_experimental_annotations,
   'XSLTProcessor': [
     "@SupportedBrowser(SupportedBrowser.CHROME)",
     "@SupportedBrowser(SupportedBrowser.FIREFOX)",
     "@SupportedBrowser(SupportedBrowser.SAFARI)",
   ],
 })
 
 
@@ skipping 184 matching lines @@
       return
     elif support_level == 'deprecated':
       return '@Deprecated'
     else:
       _logger.warn('Unknown support_level - %s:%s' % (interface_id, member_id))
 
   def Flush(self):
     json_file = open(self._api_status_path, 'w+')
     json.dump(self._types, json_file, indent=2, separators=(',', ': '), sort_keys=True)
     json_file.close()