Revert "[Experiment] Stop suppressing DragEvent"

tools/dom/scripts/htmleventgenerator.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 functionality to generate dart:html event classes."""
 
 import logging
 import monitored
 
@@ skipping 28 matching lines @@
   '*.beforeunload': ('beforeUnload', 'Event'),
   '*.blur': ('blur', 'Event'),
   '*.canplay': ('canPlay', 'Event'),
   '*.canplaythrough': ('canPlayThrough', 'Event'),
   '*.change': ('change', 'Event'),
   '*.click': ('click', 'MouseEvent'),
   '*.contextmenu': ('contextMenu', 'MouseEvent'),
   '*.copy': ('copy', 'ClipboardEvent'),
   '*.cut': ('cut', 'ClipboardEvent'),
   '*.dblclick': ('doubleClick', 'Event'),
-  '*.drag': ('drag', 'DragEvent'),
-  '*.dragend': ('dragEnd', 'DragEvent'),
-  '*.dragenter': ('dragEnter', 'DragEvent'),
-  '*.dragleave': ('dragLeave', 'DragEvent'),
-  '*.dragover': ('dragOver', 'DragEvent'),
-  '*.dragstart': ('dragStart', 'DragEvent'),
-  '*.drop': ('drop', 'DragEvent'),
+  '*.drag': ('drag', 'MouseEvent'),
+  '*.dragend': ('dragEnd', 'MouseEvent'),
+  '*.dragenter': ('dragEnter', 'MouseEvent'),
+  '*.dragleave': ('dragLeave', 'MouseEvent'),
+  '*.dragover': ('dragOver', 'MouseEvent'),
+  '*.dragstart': ('dragStart', 'MouseEvent'),
+  '*.drop': ('drop', 'MouseEvent'),
   '*.durationchange': ('durationChange', 'Event'),
   '*.emptied': ('emptied', 'Event'),
   '*.ended': ('ended', 'Event'),
   '*.error': ('error', 'Event'),
   '*.focus': ('focus', 'Event'),
   # Should be HashChangeEvent, but IE does not support it.
   '*.hashchange': ('hashChange', 'Event'),
   '*.input': ('input', 'Event'),
   '*.invalid': ('invalid', 'Event'),
   '*.keydown': ('keyDown', 'KeyboardEvent'),
@@ skipping 347 matching lines @@
     """
     key = '%s.%s' % (html_interface_name, dom_event_name)
     if key in _html_event_types:
       return _html_event_types[key]
     key = '*.%s' % dom_event_name
     if key in _html_event_types:
       return _html_event_types[key]
     _logger.warn('Cannot resolve event type for %s.%s' %
         (html_interface_name, dom_event_name))
     return None