default to port 80 for http.request

lib/http.js

@@ -1086,7 +1086,7 @@ exports._connectionListener = connectionListener;
 function Agent(options) {
   this.options = options;
   this.host = options.host;
-  this.port = options.port;
+  this.port = options.port || 80;
 
   this.queue = [];
   this.sockets = [];
@@ -1356,6 +1356,7 @@ var agents = {};
 
 
 function getAgent(host, port) {
+  port = port || 80;
   var id = host + ':' + port;
   var agent = agents[id];