Added some more information to the unload event cleanup.

src/event.js

@@ -677,6 +677,9 @@ jQuery.each( ("blur,focus,load,resize,scroll,unload,click,dblclick," +
 // Prevent memory leaks in IE
 // And prevent errors on refresh with events like mouseover in other browsers
 // Window isn't included so as not to unbind existing unload events
+// More info:
+//  - http://isaacschlueter.com/2006/10/msie-memory-leaks/
+//  - https://bugzilla.mozilla.org/show_bug.cgi?id=252542
 jQuery( window ).bind( 'unload', function(){ 
 	for ( var id in jQuery.cache )
 		// Skip the window