Remove keyIdentifier from KeyboardEvent factory constructor.

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

Index: tools/dom/templates/html/dart2js/impl_KeyboardEvent.darttemplate
diff --git a/tools/dom/templates/html/dart2js/impl_KeyboardEvent.darttemplate b/tools/dom/templates/html/dart2js/impl_KeyboardEvent.darttemplate
index 3c1a60dca526fcbf2de6e6cb4815b0f6ba0383d8..e1f21dbb1a8b74d91a523c7638b23e408d911229 100644
--- a/tools/dom/templates/html/dart2js/impl_KeyboardEvent.darttemplate
+++ b/tools/dom/templates/html/dart2js/impl_KeyboardEvent.darttemplate
@@ -14,16 +14,26 @@
  */
 $(ANNOTATIONS)$(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;
   }