Move all tests using dart:io to a separate directory

tests/standalone/src/ProcessWorkingDirectoryTest.dart

-// Copyright (c) 2012, 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.
-//
-// Process working directory test.
-
-#library("ProcessWorkingDirectoryTest");
-#import("dart:io");
-#source("ProcessTestUtil.dart");
-
-class ProcessWorkingDirectoryTest {
-  static String get fullTestFilePath() {
-    // Extract full path, since we run processes from another directory.
-    File path = new File(getProcessTestFileName());
-    Expect.isTrue(path.existsSync());
-    return path.fullPathSync();
-  }
-
-  static void testValidDirectory() {
-    Directory directory = new Directory("");
-    directory.createTempSync();
-    Expect.isTrue(directory.existsSync());
-
-    Process process = new Process.start(fullTestFilePath,
-                                        const ["0", "0", "99", "0"],
-                                        directory.path);
-
-    process.onExit = (int exitCode) {
-      Expect.equals(exitCode, 99);
-      process.close();
-      directory.deleteSync();
-    };
-
-    process.onError = (error) {
-      Expect.fail("error running process $error");
-      directory.deleteSync();
-    };
-  }
-
-  static void testInvalidDirectory() {
-    Directory directory = new Directory("");
-    directory.createTempSync();
-    Expect.isTrue(directory.existsSync());
-
-    Process process = new Process.start(fullTestFilePath,
-                                        const ["0", "0", "99", "0"],
-                                        directory.path + "/subPath");
-
-    process.onExit = (int exitCode) {
-      Expect.fail("bad process completed");
-      process.close();
-      directory.deleteSync();
-    };
-
-    process.onError = (error) {
-      Expect.isNotNull(error);
-      directory.deleteSync();
-    };
-  }
-}
-
-
-
-main() {
-  ProcessWorkingDirectoryTest.testValidDirectory();
-  ProcessWorkingDirectoryTest.testInvalidDirectory();
-}