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

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

 
-class IDBDatabaseJs extends DOMTypeJs implements IDBDatabase native "*IDBDatabase" {
+class _IDBDatabaseJs extends _DOMTypeJs implements IDBDatabase native "*IDBDatabase" {
 
   String get name() native "return this.name;";
 
   EventListener get onabort() native "return this.onabort;";
 
   void set onabort(EventListener value) native "this.onabort = value;";
 
   EventListener get onerror() native "return this.onerror;";
 
   void set onerror(EventListener value) native "this.onerror = value;";
 
   EventListener get onversionchange() native "return this.onversionchange;";
 
   void set onversionchange(EventListener value) native "this.onversionchange = value;";
 
   String get version() native "return this.version;";
 
   void addEventListener(String type, EventListener listener, [bool useCapture = null]) native;
 
   void close() native;
 
-  IDBObjectStoreJs createObjectStore(String name) native;
+  _IDBObjectStoreJs createObjectStore(String name) native;
 
   void deleteObjectStore(String name) native;
 
-  bool dispatchEvent(EventJs evt) native;
+  bool dispatchEvent(_EventJs evt) native;
 
   void removeEventListener(String type, EventListener listener, [bool useCapture = null]) native;
 
-  IDBVersionChangeRequestJs setVersion(String version) native;
+  _IDBVersionChangeRequestJs setVersion(String version) native;
 
-  IDBTransactionJs transaction(String storeName, int mode) native;
+  _IDBTransactionJs transaction(String storeName, int mode) native;
 }