Roll Observatory packages and add a roll script

packages/analyzer/lib/src/error.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.
 library error;
 
 import 'dart:collection';
 
 import 'generated/error.dart';
 
 /// The maximum line length when printing extracted source code when converting
@@ skipping 73 matching lines @@
   AnalyzerErrorGroup.fromAnalysisErrors(Iterable<AnalysisError> errors)
       : this(errors.map((e) => new AnalyzerError(e)));
 
   /// The errors in this collection.
   List<AnalyzerError> get errors =>
       new UnmodifiableListView<AnalyzerError>(_errors);
 
   String get message => toString();
   String toString() => errors.join("\n");
 }