Roll Observatory packages and add a roll script

packages/source_maps/lib/refactor.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.
 
 /// Tools to help implement refactoring like transformations to Dart code.
 ///
 /// [TextEditTransaction] supports making a series of changes to a text buffer.
 /// [guessIndent] helps to guess the appropriate indentiation for the new code.
 library source_maps.refactor;
 
@@ skipping 113 matching lines @@
     }
   }
 
   return code.substring(lineStart, whitespaceEnd);
 }
 
 const int _CR = 13;
 const int _LF = 10;
 const int _TAB = 9;
 const int _SPACE = 32;