Only set port in Host header if it's non-standard

Author: driverdan

lib/XMLHttpRequest.js

@@ -310,7 +310,10 @@ exports.XMLHttpRequest = function() {
     var uri = url.pathname + (url.search ? url.search : '');
 
     // Set the Host header or the server may reject the request
-    headers["Host"] = host + ':' + url.port;
+    headers["Host"] = host;
+    if (!((ssl && port === 443) || port === 80)) {
+      headers["Host"] += ':' + url.port;
+    }
 
     // Set Basic Auth if necessary
     if (settings.user) {