getAsEntry method Null safety

Implementation

Entry getAsEntry() {
  Entry entry = _webkitGetAsEntry() as Entry;

  if (entry.isFile!) {
    applyExtension('FileEntry', entry);
    applyExtension('webkitFileSystemFileEntry', entry);
    applyExtension('FileSystemFileEntry', entry);
  } else if (entry.isDirectory!) {
    applyExtension('DirectoryEntry', entry);
    applyExtension('webkitFileSystemDirectoryEntry', entry);
    applyExtension('FileSystemDirectoryEntry', entry);
  } else {
    applyExtension('Entry', entry);
    applyExtension('webkitFileSystemEntry', entry);
    applyExtension('FileSystemEntry', entry);
  }

  return entry;
}