Dialog: add required closing tag </button>. Fixes #8639 - jQuery 1.9.…

…0 dialog on a XHTML page is broken if buttons are defined

ui/jquery.ui.dialog.js

@@ -364,7 +364,7 @@ $.widget("ui.dialog", {
 				props = $.isFunction( props ) ?
 					{ click: props, text: name } :
 					props;
-				var button = $( "<button type='button'>" )
+				var button = $( "<button type='button'></button>" )
 					.attr( props, true )
 					.unbind( "click" )
 					.click(function() {