dispose method

@protected void dispose()

Implementation

@protected
void dispose() {
  assert(!_transitionCompleter.isCompleted,
      'Cannot dispose a $runtimeType twice.');
  dismissInternal();

  for (OverlayEntry entry in _overlayEntries) entry.remove();
  _overlayEntries.clear();
  _controller.dispose();
  _transitionCompleter.complete(_result);
}