Roll Observatory packages and add a roll script

packages/code_transformers/lib/src/resolvers.dart

 // Copyright (c) 2014, 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 code_transformers.src.resolvers;
 
 import 'dart:async';
 import 'package:barback/barback.dart';
 
 import 'package:analyzer/src/generated/engine.dart' show AnalysisOptions;
@@ skipping 102 matching lines @@
         resolver.release();
       });
     });
   }
 
   /// Invoked when the resolver is ready to be processed.
   ///
   /// Return a Future to indicate when apply is completed.
   applyResolver(Transform transform, Resolver resolver);
 }