Roll Observatory packages and add a roll script

packages/yaml/lib/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;
 
 import 'src/loader.dart';
 import 'src/style.dart';
 import 'src/yaml_document.dart';
 import 'src/yaml_exception.dart';
@@ skipping 63 matching lines @@
 /// implementation; for details, see the [YamlMap] class.
 ///
 /// In future versions, maps will instead be [HashMap]s with a custom equality
 /// operation.
 ///
 /// If [sourceUrl] is passed, it's used as the URL from which the YAML
 /// originated for error reporting. It can be a [String], a [Uri], or `null`.
 YamlList loadYamlStream(String yaml, {sourceUrl}) {
   var loader = new Loader(yaml, sourceUrl: sourceUrl);
 
-  var documents = [];
+  var documents = <YamlDocument>[];
   var document = loader.load();
   while (document != null) {
     documents.add(document);
     document = loader.load();
   }
 
+  // TODO(jmesserly): the type on the `document` parameter is a workaround for:
+  // https://github.com/dart-lang/dev_compiler/issues/203
   return new YamlList.internal(
-      documents.map((document) => document.contents).toList(),
+      documents.map((YamlDocument document) => document.contents).toList(),
       loader.span,
       CollectionStyle.ANY);
 }
 
 /// Loads a stream of documents from a YAML string.
 ///
 /// This is like [loadYamlStream], except that it returns [YamlDocument]s with
 /// metadata wrapping the document contents.
 List<YamlDocument> loadYamlDocuments(String yaml, {sourceUrl}) {
   var loader = new Loader(yaml, sourceUrl: sourceUrl);
 
-  var documents = [];
+  var documents = <YamlDocument>[];
   var document = loader.load();
   while (document != null) {
     documents.add(document);
     document = loader.load();
   }
 
   return documents;
 }