Move more files around.

test/util/one_off_handler_test.dart

 // Copyright (c) 2015, 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.
 
 import 'dart:async';
 
 import 'package:shelf/shelf.dart' as shelf;
 import 'package:unittest/src/util/one_off_handler.dart';
 import 'package:unittest/unittest.dart';
 
@@ skipping 64 matching lines @@
       expect(response.readAsString(), completion(equals("one")));
 
       request = new shelf.Request("GET", Uri.parse("http://localhost/$path3"));
       return _handle(request);
     }).then((response) {
       expect(response.statusCode, equals(200));
       expect(response.readAsString(), completion(equals("three")));
     });
   });
 }