[Test] Update 'default' SixSpeed benchmark to use different processes.

test/js-perf-test/SixSpeed/defaults/defaults.js

-// Copyright 2016 the V8 project authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-// This benchmark is based on the six-speed benchmark build output.
-// Copyright 2014 Kevin Decker <https://github.com/kpdecker/six-speed/>
-
-
-new BenchmarkSuite('Defaults-ES5', [1000], [
-  new Benchmark('ES5', false, false, 0, ES5),
-]);
-
-new BenchmarkSuite('Defaults-ES6', [1000], [
-  new Benchmark('ES6', false, false, 0, ES6),
-]);
-
-// ----------------------------------------------------------------------------
-// Benchmark: ES5
-// ----------------------------------------------------------------------------
-
-function ES5() {
-  "use strict";
-  function fn(arg, other) {
-    arg = arg === undefined ? 1 : arg;
-    other = other === undefined ? 3 : other;
-    return other;
-  }
-
-  fn();
-  fn(2);
-  fn(2, 4);
-}
-
-// ----------------------------------------------------------------------------
-// Benchmark: ES6
-// ----------------------------------------------------------------------------
-
-function ES6() {
-  "use strict";
-  function fn(arg = 1, other = 3) {
-    return other;
-  }
-
-  fn();
-  fn(2);
-  fn(2, 4);
-}