Update page-load.js

Added true parameter to request.open (line 266) method so it literally specifies that it is async request which fixed issue with browsers other than IE and Tumblr

Author: vDeggial

js/page-load.js

@@ -263,7 +263,7 @@ proto.stopPrefill = function() {
 
 function request( url, responseType, onLoad, onError ) {
   var req = new XMLHttpRequest();
-  req.open( 'GET', url );
+  req.open( 'GET', url, true );
   // set responseType document to return DOM
   req.responseType = responseType || '';