[Test] Update all SixSpeed tests to run in separate processes.

test/js-perf-test/SixSpeed/spread/spread.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('Spread-ES5', [1000], [
-  new Benchmark('ES5', false, false, 0, ES5),
-]);
-
-new BenchmarkSuite('Spread-Traceur', [1000], [
-  new Benchmark('Traceur', false, false, 0, Traceur),
-]);
-
-new BenchmarkSuite('Spread-ES6', [1000], [
-  new Benchmark('ES6', false, false, 0, ES6),
-]);
-
-// ----------------------------------------------------------------------------
-// Benchmark: ES5
-// ----------------------------------------------------------------------------
-
-function ES5() {
-  "use strict";
-  return Math.max.apply(Math, [1,2,3]);
-}
-
-// ----------------------------------------------------------------------------
-// Benchmark: Traceur
-// ----------------------------------------------------------------------------
-
-function checkObjectCoercible(v) {
-  "use strict";
-  if (v === null || v === undefined) {
-    throw new $TypeError('Value cannot be converted to an Object');
-  }
-  return v;
-}
-
-function spread() {
-  "use strict";
-  var rv = [],
-      j = 0,
-      iterResult;
-  for (var i = 0; i < arguments.length; i++) {
-    var valueToSpread = checkObjectCoercible(arguments[i]);
-    if (typeof valueToSpread[Symbol.iterator] !== 'function') {
-      throw new TypeError('Cannot spread non-iterable object.');
-    }
-    var iter = valueToSpread[Symbol.iterator]();
-    while (!(iterResult = iter.next()).done) {
-      rv[j++] = iterResult.value;
-    }
-  }
-  return rv;
-}
-
-function Traceur() {
-  "use strict";
-  var $__0;
-  return ($__0 = Math).max.apply($__0, spread([1, 2, 3]));
-}
-
-// ----------------------------------------------------------------------------
-// Benchmark: ES6
-// ----------------------------------------------------------------------------
-
-function ES6() {
-  "use strict";
-  return Math.max(...[1,2,3]);
-}