isolates refactor: this change introduces 'dart:isolate' as a library. This is a

tests/standalone/src/DirectoryTest.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.
 //
 // Directory listing test.
 
 #import("dart:io");
+#import("dart:isolate");
 
 class DirectoryTest {
   static void testListing() {
     bool listedDir = false;
     bool listedFile = false;
 
     Directory directory = new Directory("");
     directory.createTempSync();
     Directory subDirectory = new Directory("${directory.path}/subdir");
     Expect.isFalse(subDirectory.existsSync());
@@ skipping 458 matching lines @@
   dir.createTemp();
 }
 
 
 main() {
   DirectoryTest.testMain();
   NestedTempDirectoryTest.testMain();
   testCreateTempErrorSync();
   testCreateTempError();
 }