net: add length check when normalizing args

This helps to prevent possible deoptimizations that arise when trying
to access nonexistent indices.

PR-URL: https://github.com/nodejs/node/pull/8112
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

lib/net.js

@@ -73,7 +73,9 @@ exports.connect = exports.createConnection = function() {
 function normalizeConnectArgs(args) {
   var options = {};
 
-  if (args[0] !== null && typeof args[0] === 'object') {
+  if (args.length === 0) {
+    return [options];
+  } else if (args[0] !== null && typeof args[0] === 'object') {
     // connect(options, [cb])
     options = args[0];
   } else if (isPipeName(args[0])) {
@@ -82,7 +84,7 @@ function normalizeConnectArgs(args) {
   } else {
     // connect(port, [host], [cb])
     options.port = args[0];
-    if (typeof args[1] === 'string') {
+    if (args.length > 1 && typeof args[1] === 'string') {
       options.host = args[1];
     }
   }