Updating KeyboardEvent constructor to use named parameters.

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.
 
 
 $(ANNOTATIONS)class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
 
-  factory $CLASSNAME(String type, Window view,
-      [bool canBubble = true, bool cancelable = true,
-      String keyIdentifier = "", int keyLocation = 1, bool ctrlKey = false,
-      bool altKey = false, bool shiftKey = false, bool metaKey = false,
-      bool altGraphKey = false]) {
+  factory $CLASSNAME(String type,
+      {Window view, bool canBubble: true, bool cancelable: true,
+      String keyIdentifier: "", int keyLocation: 1, bool ctrlKey: false,
+      bool altKey: false, bool shiftKey: false, bool metaKey: false,
+      bool altGraphKey: false}) {
+    if (view == null) {
+      view = window;
+    }
     final e = document.$dom_createEvent("KeyboardEvent");
     e.$dom_initKeyboardEvent(type, canBubble, cancelable, view, keyIdentifier,
         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) {
@@ skipping 13 matching lines @@
     }
   }
 
   @DomName('KeyboardEvent.keyCode')
   int get keyCode => $dom_keyCode;
 
   @DomName('KeyboardEvent.charCode')
   int get charCode => $dom_charCode;
 $!MEMBERS
 }