Make KeyboardEvent have direct fields for keyCode/charCode, as they're no longer inherited from UIE…

tools/dom/templates/html/dart2js/impl_KeyboardEvent.darttemplate

 // 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.
 
 
 /**
  * An event that describes user interaction with the keyboard.
  *
  * The [type] of the event identifies what kind of interaction occurred.
  *
@@ skipping 47 matching lines @@
           ctrlKey, altKey, shiftKey, metaKey);
     } else {
       // initKeyboardEvent is for all other browsers.
       JS('void', '#.initKeyboardEvent(#, #, #, #, #, #, #, #, #, #)', this,
           type, canBubble, cancelable, view, keyIdentifier, location,
           ctrlKey, altKey, shiftKey, metaKey);
     }
   }
 
   @DomName('KeyboardEvent.keyCode')
-  int get keyCode => _keyCode;
+  final int keyCode;
 
   @DomName('KeyboardEvent.charCode')
-  int get charCode => _charCode;
+  final int charCode;
 
   @DomName('KeyboardEvent.which')
   int get which => _which;
 $!MEMBERS
 }