Drupal collapsible fieldset script with trigger to resize TinyMCE

/**
 * OVERWRITES Drupal.toggleFieldset in /misc/collapse.js
 *
 * Modified to trigger autoresize on tinyMCE textareas inside collapsed fieldsets
 */
Drupal.toggleFieldset = function(fieldset) {
  if ($(fieldset).is('.collapsed')) {
    // Action div containers are processed separately because of a IE bug
    // that alters the default submit button behavior.
    var content = $('> div:not(.action)', fieldset);
    $(fieldset).removeClass('collapsed');
    content.hide();
    content.slideDown( {
      duration: 'fast',
      easing: 'linear',
      complete: function() {
        Drupal.collapseScrollIntoView(this.parentNode);
        this.parentNode.animating = false;
        $('div.action', fieldset).show();
 
        // >>>>
        var editors = $(fieldset).find('.mceEditor');
        $.each(editors, function() {
            var instance = tinyMCE.get($(this).attr('id').replace('_parent', ''));
 
            // Add a min height it it doesn't have one yet
            if (instance.plugins.autoresize && instance.plugins.autoresize.autoresize_min_height < 50) {
                instance.plugins.autoresize.autoresize_min_height = 50;
            }
            // Trigger the resize
            instance.execCommand('mceAutoResize');
        });
	// >>>
      },
      step: function() {
        // Scroll the fieldset into view
        Drupal.collapseScrollIntoView(this.parentNode);
      }
    });
  }
  else {
    $('div.action', fieldset).hide();
    var content = $('> div:not(.action)', fieldset).slideUp('fast', function() {
      $(this.parentNode).addClass('collapsed');
      this.parentNode.animating = false;
    });
  }
};