Add ClipboardEvent for Firefox.

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 451 matching lines @@
   'Window.webkitRequestFileSystem': _file_system_annotations,
   'Window.webkitResolveLocalFileSystemURL': _file_system_annotations,
   'Element.createShadowRoot': [
     "@SupportedBrowser(SupportedBrowser.CHROME, '25')",
     "@Experimental()",
   ],
   'Element.ontransitionend': _all_but_ie9_annotations,
   # Placeholder to add experimental flag, implementation for this is
   # pending in a separate CL.
   'Element.webkitMatchesSelector': ['@Experimental()'],
-  'Event.clipboardData': _webkit_experimental_annotations,
+  'Event.clipboardData': [
+    "@SupportedBrowser(SupportedBrowser.CHROME)",
+    "@SupportedBrowser(SupportedBrowser.FIREFOX)",
+    "@SupportedBrowser(SupportedBrowser.SAFARI)",
+    "@Experimental()",
+  ],
   'FormData': _all_but_ie9_annotations,
   'HashChangeEvent': [
     "@SupportedBrowser(SupportedBrowser.CHROME)",
     "@SupportedBrowser(SupportedBrowser.FIREFOX)",
     "@SupportedBrowser(SupportedBrowser.SAFARI)",
   ],
   'History.pushState': _history_annotations,
   'History.replaceState': _history_annotations,
   'HTMLContentElement': _shadow_dom_annotations,
   'HTMLDataListElement': _all_but_ie9_annotations,
@@ skipping 336 matching lines @@
       pass
     else:
       _logger.warn('Unknown support_level - %s:%s' % (interface_id, member_id))
 
     return annotations
 
   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()