Restructure YAML package suitable for pub lish

utils/tests/pub/test_pub.dart

 // Copyright (c) 2012, 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.
 
 /**
  * Test infrastructure for testing pub. Unlike typical unit tests, most pub
  * tests are integration tests that stage some stuff on the file system, run
  * pub, and then validate the results. This library provides an API to build
  * tests like that.
  */
@@ skipping 10 matching lines @@
 import '../../lib/file_system.dart' as fs;
 import '../../pub/entrypoint.dart';
 import '../../pub/git_source.dart';
 import '../../pub/hosted_source.dart';
 import '../../pub/io.dart';
 import '../../pub/path.dart' as path;
 import '../../pub/sdk_source.dart';
 import '../../pub/system_cache.dart';
 import '../../pub/utils.dart';
 import '../../pub/validator.dart';
-import '../../pub/yaml/yaml.dart';
+import '../../pub/yaml/lib/yaml.dart';
 
 /**
  * Creates a new [FileDescriptor] with [name] and [contents].
  */
 FileDescriptor file(Pattern name, String contents) =>
     new FileDescriptor(name, contents);
 
 /**
  * Creates a new [DirectoryDescriptor] with [name] and [contents].
  */
@@ skipping 1622 matching lines @@
 /// calling [completion] is unnecessary.
 void expectLater(Future actual, matcher, {String reason,
     FailureHandler failureHandler, bool verbose: false}) {
   _schedule((_) {
     return actual.transform((value) {
       expect(value, matcher, reason: reason, failureHandler: failureHandler,
           verbose: false);
     });
   });
 }