anchor.diff:  class FileSystemAccess extends Protocol {
     Future<List<File>> list(String path) {
       var completer = new Completer();
  -    window.navigator.persistentStorage.requestQuota(size);
       window.requestFileSystem(size, persistent: persistent).then((fs){
         List<File> files = new List<File>();
         DirectoryEntry root = fs.root;
  
positive.code:   }
  
    Stream<List<int>> open(String path) {
      // TODO: implement open
    }
  
    StreamConsumer openWrite(String path) {
  
negative.code:   }
  
    Future connect() {
      //on connect request quota from browser
      window.navigator.persistentStorage.requestQuota(size);
      return new Completer()..complete().future;
    }
  
  