Support for rewinddir().
bool TRUE on success.
Overrides PhpStreamWrapperInterface::dir_rewinddir
http://php.net/manual/streamwrapper.dir-rewinddir.php
public function dir_rewinddir() {
rewinddir($this->handle);
// We do not really have a way to signal a failure as rewinddir() does not
// have a return value and there is no way to read a directory handler
// without advancing to the next file.
return TRUE;
}