Move all tests using dart:io to a separate directory

tests/standalone/src/ProcessTestUtil.dart

-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-String getPlatformOutDir() {
-  var os = new Platform().operatingSystem();
-  if (os == 'linux') return 'out/';
-  if (os == 'macos') return 'xcodebuild/';
-  return '';  // Windows.
-}
-
-String getPlatformExecutableExtension() {
-  var os = new Platform().operatingSystem();
-  if (os == 'windows') return '.exe';
-  return '';  // Linux and Mac OS.
-}
-
-String getProcessTestFileName() {
-  var outDir = getPlatformOutDir();
-  var extension = getPlatformExecutableExtension();
-  var names = ['${outDir}Release_ia32/process_test$extension',
-               '${outDir}Debug_ia32/process_test$extension'];
-
-  for (var name in names) {
-    if (new File(name).existsSync()) {
-      return name;
-    }
-  }
-  Expect.fail('Could not find the process_test executable.');
-}
-
-String getDartFileName() {
-  var outDir = getPlatformOutDir();
-  var extension = getPlatformExecutableExtension();
-  var names = ['${outDir}Release_ia32/dart$extension',
-               '${outDir}Debug_ia32/dart$extension'];
-
-  for (var name in names) {
-    if (new File(name).existsSync()) {
-      return name;
-    }
-  }
-  Expect.fail('Could not find the dart executable.');
-}