MDL-21535 adding missing M.util.in_array

lib/javascript-static.js

@@ -46,6 +46,15 @@ M.util.create_UFO_object = function (eid, FO) {
     UFO.create(FO, eid);
 }
 
+M.util.in_array = function(item, array){
+    for( var i = 0; i<array.length; i++){
+        if(item==array[i]){
+            return true;
+        }
+    }
+    return false;
+}
+
 /**
  * Init a collapsible region, see print_collapsible_region in weblib.php
  * @param {YUI} Y YUI3 instance with all libraries loaded