Dart: Reorganize files

mojo/dart/apptests/dart_apptests/lib/src/file_apptests.dart

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 library file_apptests;
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 
@@ skipping 169 matching lines @@
       }
       expect(exceptionCaught, isTrue);
       // Verify that everything has been deleted.
       // TODO(johnmccutchan): Uncomment once recursive deletion is implemented.
       // expect(await directory.exists(), isFalse);
       // expect(await newChildFile.exists(), isFalse);
       // expect(await childDirectory.exists(), isFalse);
     });
   });
 }