Changing to file level use strict statement

lib/helpers/urlIsSameOrigin.js

@@ -1,3 +1,5 @@
+'use strict';
+
 var utils = require('./../utils');
 var msie = /(msie|trident)/i.test(navigator.userAgent);
 var urlParsingNode = document.createElement('a');
@@ -10,7 +12,6 @@ var originUrl;
  * @returns {Object}
  */
 function urlResolve(url) {
-  'use strict';
   var href = url;
 
   if (msie) {
@@ -45,7 +46,6 @@ originUrl = urlResolve(window.location.href);
  * @returns {boolean} True if URL shares the same origin, otherwise false
  */
 module.exports = function urlIsSameOrigin(requestUrl) {
-  'use strict';
   var parsed = (utils.isString(requestUrl)) ? urlResolve(requestUrl) : requestUrl;
   return (parsed.protocol === originUrl.protocol &&
         parsed.host === originUrl.host);