Make sure that the unload event doesn't leak in IE - use jQuery's binding...

Make sure that the unload event doesn't leak in IE - use jQuery's binding mechanism to make that happen.

src/event.js

@@ -1154,7 +1154,7 @@ jQuery.each( ("blur focus focusin focusout load resize scroll unload click dblcl
 // More info:
 //  - http://isaacschlueter.com/2006/10/msie-memory-leaks/
 if ( window.attachEvent && !window.addEventListener ) {
-	window.attachEvent("onunload", function() {
+	jQuery(window).bind("unload", function() {
 		for ( var id in jQuery.cache ) {
 			if ( jQuery.cache[ id ].handle ) {
 				// Try/Catch is to handle iframes being unloaded, see #4280