Roll Observatory packages and add a roll script

packages/code_transformers/lib/src/remove_sourcemap_comment.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.
 
 /// Transformer that removes any sourcemap comments from javascript files.
 library code_transformers.src.remove_sourcemap_comment;
 
 import 'package:barback/barback.dart';
 
 /// Transformer that removes any sourcemap comments from javascript files.
@@ skipping 11 matching lines @@
     return transform.readInputAsString(id).then((file) {
       if (file.contains(_SOURCE_MAP_COMMENT)) {
         transform.addOutput(
             new Asset.fromString(id, file.replaceAll(_SOURCE_MAP_COMMENT, '')));
       }
     });
   }
 }
 
 final RegExp _SOURCE_MAP_COMMENT = new RegExp(r'\n\s*\/\/# sourceMappingURL.*');