http: add callback is function check

We were checking that the callback existed, but not checking that it was a function. In `setTimeout`, if callback is truthy but not a function, throw a TypeError Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com> Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> PR-URL: #3090

Author: jasnell

lib/_http_outgoing.js

@@ -89,8 +89,12 @@ exports.OutgoingMessage = OutgoingMessage;
 
 
 OutgoingMessage.prototype.setTimeout = function(msecs, callback) {
- if (callback)
+
+ if (callback) {
+ if (typeof callback !== 'function')
+ throw new TypeError('callback must be a function');
  this.on('timeout', callback);
+ }
 
  if (!this.socket) {
  this.once('socket', function(socket) {