Update utils to new library syntax.

utils/pub/yaml/yaml.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.
 
-#library("yaml");
+library yaml;
 
-#import('dart:math', prefix: 'Math');
+import 'dart:math' as Math;
 
-#import("deep_equals.dart");
+import 'deep_equals.dart';
 
-#source("yaml_map.dart");
-#source("model.dart");
-#source("parser.dart");
-#source("visitor.dart");
-#source("composer.dart");
-#source("constructor.dart");
+part 'yaml_map.dart';
+part 'model.dart';
+part 'parser.dart';
+part 'visitor.dart';
+part 'composer.dart';
+part 'constructor.dart';
 
 /**
  * Loads a single document from a YAML string. If the string contains more than
  * one document, this throws an error.
  *
  * The return value is mostly normal Dart objects. However, since YAML mappings
  * support some key types that the default Dart map implementation doesn't
  * (null, NaN, booleans, lists, and maps), all maps in the returned document are
  * YamlMaps. These have a few small behavioral differences from the default Map
  * implementation; for details, see the YamlMap class.
@@ skipping 21 matching lines @@
 }
 
 /** An error thrown by the YAML processor. */
 class YamlException implements Exception {
   String msg;
 
   YamlException(this.msg);
 
   String toString() => msg;
 }