Allow DirectoryDescriptor.load to load a file next to a directory.

pkg/scheduled_test/test/descriptor/file_test.dart

 // Copyright (c) 2013, 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 'dart:io';
 
 import 'package:pathos/path.dart' as path;
 import 'package:scheduled_test/descriptor.dart' as d;
 import 'package:scheduled_test/scheduled_test.dart';
@@ skipping 96 matching lines @@
   }, passing: ['test 2']);
 
   expectTestsPass("file().read() returns the contents of the file as a stream",
       () {
     test('test', () {
       expect(byteStreamToString(d.file('name.txt', 'contents').read()),
           completion(equals('contents')));
     });
   });
 
-  expectTestsPass("file().load() throws an error", () {
-    test('test', () {
-      expect(d.file('name.txt', 'contents').load('path').toList(),
-          throwsA(equals("Can't load 'path' from within 'name.txt': not a "
-                         "directory.")));
-    });
-  });
-
   expectTestsPass("file().describe() returns the filename", () {
     test('test', () {
       expect(d.file('name.txt', 'contents').describe(), equals('name.txt'));
     });
   });
 
   expectTestsPass('binaryFile().create() creates a file', () {
     test('test', () {
       scheduleSandbox();
 
@@ skipping 133 matching lines @@
 
     test('test 2', () {
       expect(errors, everyElement(new isInstanceOf<ScheduleError>()));
       expect(errors.map((e) => e.error.message), equals([
         "Expected: contains <12>\n"
         "     But: was [98, 97, 114, 102, 111, 111, 98, 97, 122].\n"
       ]), verbose: true);
     });
   }, passing: ['test 2']);
 }