Dialog: Don't use .attr( props, true ).

(cherry picked from commit a8de99c)

ui/jquery.ui.dialog.js

@@ -369,15 +369,18 @@ $.widget("ui.dialog", {
 		}
 		if ( hasButtons ) {
 			$.each( buttons, function( name, props ) {
+				var button, click;
 				props = $.isFunction( props ) ?
 					{ click: props, text: name } :
 					props;
-				var button = $( "<button type='button'></button>" )
-					.attr( props, true )
-					.unbind( "click" )
-					.click(function() {
-						props.click.apply( that.element[0], arguments );
-					})
+				// Default to a non-submitting button
+				props = $.extend( { type: "button" }, props );
+				// Change the context for the click callback to be the main element
+				click = props.click;
+				props.click = function() {
+					click.apply( that.element[0], arguments );
+				};
+				button = $( "<button></button>", props )
 					.appendTo( that.uiButtonSet );
 				if ( $.fn.button ) {
 					button.button();