Remove keyIdentifier from KeyboardEvent factory constructor.

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.
  *
  * See also:
  *
  * * [KeyboardEvent](https://developer.mozilla.org/en/DOM/KeyboardEvent) at MDN.
  */
 $(ANNOTATIONS)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
 
+  /** 
+   * Programmatically create a KeyboardEvent. 
+   *
+   * Due to browser differences, keyCode, charCode, or keyIdentifier values
+   * cannot be specified in this base level constructor. This constructor
+   * enables the user to programmatically create and dispatch a [KeyboardEvent],
+   * but it will not contain any particular key content. For programmatically
+   * creating keyboard events with specific key value contents, see the custom
+   * Event [KeyEvent]. 
+   */
   factory $CLASSNAME(String type,
       {Window view, bool canBubble: true, bool cancelable: true,
-      String keyIdentifier: "", int keyLocation: 1, bool ctrlKey: false,
+      int keyLocation: 1, bool ctrlKey: false,
       bool altKey: false, bool shiftKey: false, bool metaKey: false,
       bool altGraphKey: false}) {
     if (view == null) {
       view = window;
     }
     final e = document.$dom_createEvent("KeyboardEvent");
-    e.$dom_initKeyboardEvent(type, canBubble, cancelable, view, keyIdentifier,
+    e.$dom_initKeyboardEvent(type, canBubble, cancelable, view, "",
         keyLocation, ctrlKey, altKey, shiftKey, metaKey, altGraphKey);
     return e;
   }
 
   @DomName('KeyboardEvent.initKeyboardEvent')
   void $dom_initKeyboardEvent(String type, bool canBubble, bool cancelable,
       Window view, String keyIdentifier, int keyLocation, bool ctrlKey,
       bool altKey, bool shiftKey, bool metaKey, bool altGraphKey) {
     if (JS('bool', 'typeof(#.initKeyEvent) == "function"', this)) {
       // initKeyEvent is only in Firefox (instead of initKeyboardEvent). It has
@@ skipping 11 matching lines @@
     }
   }
 
   @DomName('KeyboardEvent.keyCode')
   int get keyCode => $dom_keyCode;
 
   @DomName('KeyboardEvent.charCode')
   int get charCode => $dom_charCode;
 $!MEMBERS
 }