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

pkg/scheduled_test/test/descriptor/nothing_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 66 matching lines @@
     });
 
     test('test 2', () {
       expect(errors, everyElement(new isInstanceOf<ScheduleError>()));
       expect(errors.length, equals(1));
       expect(errors.first.error,
           matches(r"^Expected nothing to exist at '[^']+[\\/]dir', but found a "
               r"directory\.$"));
     });
   }, passing: ['test 2']);
-
-  expectTestsPass("nothing().load() fails", () {
-    test('test', () {
-      scheduleSandbox();
-
-      expect(d.nothing('name.txt').load('path').toList(),
-          throwsA(equals("Nothing descriptors don't support load().")));
-    });
-  });
-
-  expectTestsPass("nothing().read() fails", () {
-    test('test', () {
-      scheduleSandbox();
-
-      expect(d.nothing('name.txt').read().toList(),
-          throwsA(equals("Nothing descriptors don't support read().")));
-    });
-  });
 }