Remove support for attribute event listeners.

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

 
 class IDBDatabase native "IDBDatabase" {
 
   String name;
 
-  EventListener onabort;
-
-  EventListener onerror;
-
-  EventListener onversionchange;
-
   String version;
 
   void addEventListener(String type, EventListener listener, [bool useCapture = null]) native;
 
   void close() native;
 
   IDBObjectStore createObjectStore(String name) native;
 
   void deleteObjectStore(String name) native;
 
   bool dispatchEvent(Event evt) native;
 
   void removeEventListener(String type, EventListener listener, [bool useCapture = null]) native;
 
   IDBVersionChangeRequest setVersion(String version) native;
 
   IDBTransaction transaction(String storeName, int mode) native;
 
   var dartObjectLocalStorage;
 
   String get typeName() native;
 }