Add the ability to get the current directory

tests/standalone/src/io/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 {
@@ skipping 335 matching lines @@
           // Delete the file, and then delete the directory.
           file.delete(() {
             tempDirectory.deleteSync();
             Expect.isFalse(tempDirectory.existsSync());
           });
         });
       });
     });
   }
 
+  static void testCurrent() {
+    Directory current = new Directory.current();
+    if (new Platform().operatingSystem() != "windows") {
+      Expect.equals("/", current.path.substring(0, 1));

[Bill Hesse, 2012/03/08 11:26:34]

Why can't we test that Directory.current() is the same as
Directory(".").fullPath?

I always used Directory('.') for the current directory - Why isn't that
sufficient?  Or just Directory('.').fullPath()?

+    }
+  }
+
   static void testMain() {
     testListing();
     testListNonExistent();
     testListTooLongName();
     testDeleteNonExistent();
     testDeleteTooLongName();
     testDeleteNonExistentSync();
     testDeleteTooLongNameSync();
     testExistsCreateDelete();
     testExistsCreateDeleteSync();
     testCreateTemp();
     testCreateDeleteTemp();
+    testCurrent();
   }
 }
 
 
 class NestedTempDirectoryTest {
   List<Directory> createdDirectories;
   Directory current;
 
   NestedTempDirectoryTest.run()
       : createdDirectories = new List<Directory>(),
@@ skipping 72 matching lines @@
   dir.createTemp(() => resultPort.toSendPort().send("success"));
 }
 
 
 main() {
   DirectoryTest.testMain();
   NestedTempDirectoryTest.testMain();
   testCreateTempErrorSync();
   testCreateTempError();
 }