Roll Observatory packages and add a roll script

packages/charted/lib/charts/src/chart_data_impl.dart

 //
 // Copyright 2014 Google Inc. All rights reserved.
 //
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file or at
 // https://developers.google.com/open-source/licenses/bsd
 //
 
 part of charted.charts;
 
@@ skipping 116 matching lines @@
         strBuffer.write(' ' * lengthDiff + ' ${data} |');
 
         if (i == row.length - 1) {
           strBuffer.write('\n' + '-' * totalLength + '\n');
         }
       }
     }
     return strBuffer.toString();
   }
 }