Moved global XMLDocument annotation

From modules\utils.js to modules\tester.js

@@ -849,6 +849,7 @@ Tester.prototype.assertType = function assertType(subject, type, message) {
  */
 Tester.prototype.assertInstanceOf = function assertInstanceOf(subject, constructor, message) {
     "use strict";
+    /*global XMLDocument */
     if (utils.betterTypeOf(constructor) !== "function") {
         throw new CasperError('Subject is null or undefined.');
     }

@@ -80,7 +80,6 @@ exports.betterTypeOf = betterTypeOf;
  */
 function betterInstanceOf(input, constructor) {
     "use strict";
-    /*global XMLDocument */
     /*jshint eqnull:true, eqeqeq:false */
     while (input != null) {
       if (input == constructor.prototype) {