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

test/js-perf-test/SixSpeed/spread/run.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.
-
-load('../../base.js');
-load('spread.js');
-
-var success = true;
-
-function PrintResult(name, result) {
-  print(name + '(Score): ' + result);
-}
-
-
-function PrintError(name, error) {
-  PrintResult(name, error);
-  success = false;
-}
-
-
-BenchmarkSuite.config.doWarmup = undefined;
-BenchmarkSuite.config.doDeterministic = undefined;
-
-BenchmarkSuite.RunSuites({ NotifyResult: PrintResult,
-                           NotifyError: PrintError });