fixes #735. Problem is that when you do this.style['zIndex'] it gets …

…0 incorrectly.

Source/Element/Element.Style.js

@@ -84,7 +84,7 @@ Element.implement({
 		}
 		property = property.camelCase();
 		var result = this.style[property];
-		if (!$chk(result)){
+		if (!$chk(result) || property == 'zIndex'){
 			result = [];
 			for (var style in Element.ShortStyles){
 				if (property != style) continue;