benchmark: add ClientRequest creation benchmark

PR-URL: https://github.com/nodejs/node/pull/10654
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Fedor Indutny <fedor.indutny@gmail.com>

benchmark/http/create-clientrequest.js

@@ -0,0 +1,23 @@
+'use strict';
+
+var common = require('../common.js');
+var ClientRequest = require('http').ClientRequest;
+
+var bench = common.createBenchmark(main, {
+  pathlen: [1, 8, 16, 32, 64, 128],
+  n: [1e6]
+});
+
+function main(conf) {
+  var pathlen = +conf.pathlen;
+  var n = +conf.n;
+
+  var path = '/'.repeat(pathlen);
+  var opts = { path: path, createConnection: function() {} };
+
+  bench.start();
+  for (var i = 0; i < n; i++) {
+    new ClientRequest(opts);
+  }
+  bench.end(n);
+}