Make dart:dom implementation types private so they don't muddle the docs.

client/dom/generated/src/frog/Notification.dart

 
-class NotificationJs extends DOMTypeJs implements Notification native "*Notification" {
+class _NotificationJs extends _DOMTypeJs implements Notification native "*Notification" {
 
   String get dir() native "return this.dir;";
 
   void set dir(String value) native "this.dir = value;";
 
   String get replaceId() native "return this.replaceId;";
 
   void set replaceId(String value) native "this.replaceId = value;";
 
   void addEventListener(String type, EventListener listener, [bool useCapture = null]) native;
 
   void cancel() native;
 
-  bool dispatchEvent(EventJs evt) native;
+  bool dispatchEvent(_EventJs evt) native;
 
   void removeEventListener(String type, EventListener listener, [bool useCapture = null]) native;
 
   void show() native;
 }