Dart: Reorganize files

mojo/dart/apptests/dart_apptests/lib/src/versioning_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 versioning_apptests;
 
 import 'dart:async';
 
 import 'package:mojo_apptest/apptest.dart';
 import 'package:mojo/application.dart';
@@ skipping 119 matching lines @@
       } catch (e) {
         exceptionCaught = true;
       }
       expect(exceptionCaught, isTrue);
 
       // No need to disconnect from database because we were disconnected by
       // the call to a version 2 method.
     });
   });
 }