benchmark: remove forced optimization from util

This removes all instances of %OptimizeFunctionOnNextCall from util
benchmarks

PR-URL: https://github.com/nodejs/node/pull/9615
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

benchmark/util/format.js

@@ -2,7 +2,6 @@
 
 const util = require('util');
 const common = require('../common');
-const v8 = require('v8');
 const types = [
   'string',
   'number',
@@ -29,12 +28,6 @@ function main(conf) {
 
   const input = inputs[type];
 
-  v8.setFlagsFromString('--allow_natives_syntax');
-
-  util.format(input[0], input[1]);
-  eval('%OptimizeFunctionOnNextCall(util.format)');
-  util.format(input[0], input[1]);
-
   bench.start();
   for (var i = 0; i < n; i++) {
     util.format(input[0], input[1]);