code: function css_defaultDisplay( nodeName ) {
  	var doc = document,
  		display = elemdisplay[ nodeName ];
  
  	if ( !display ) {
  		display = actualDisplay( nodeName, doc );
  
  		// If the simple way fails, read from inside an iframe
  		if ( display === "none" || !display ) {
  			// Use the already-created iframe if possible
  			iframe = ( iframe ||
  				jQuery("<iframe frameborder='0' width='0' height='0'/>")
  				.css( "cssText", "display:block !important" )
  			).appendTo( doc.documentElement );
  
  			// Always write a new HTML skeleton so Webkit and Firefox don't choke on reuse
  			doc = ( iframe[0].contentWindow || iframe[0].contentDocument ).document;
  			doc.write("<!doctype html><html><body>");
  			doc.close();
  
  			display = actualDisplay( nodeName, doc );
  			iframe.detach();
  		}
  
  		// Store the correct default display
  		elemdisplay[ nodeName ] = display;
  	}
  
  	return display;
  }
docs: Try to determine the default display value of an element