Remove generated directories with 100s of files.

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

-
-class _IDBDatabaseJs extends _DOMTypeJs implements IDBDatabase native "*IDBDatabase" {
-
-  final String name;
-
-  final List<String> objectStoreNames;
-
-  EventListener onabort;
-
-  EventListener onerror;
-
-  EventListener onversionchange;
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-  final String version;
-
-  void addEventListener(String type, EventListener listener, [bool useCapture = null]) native;
-
-  void close() native;
-
-  _IDBObjectStoreJs createObjectStore(String name) native;
-
-  void deleteObjectStore(String name) native;
-
-  bool dispatchEvent(_EventJs evt) native;
-
-  void removeEventListener(String type, EventListener listener, [bool useCapture = null]) native;
-
-  _IDBVersionChangeRequestJs setVersion(String version) native;
-
-  _IDBTransactionJs transaction(var storeName_OR_storeNames, [int mode = null]) native;
-}