Roll Observatory packages and add a roll script

packages/charted/lib/charts/cartesian_renderers/bar_chart_renderer.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 215 matching lines @@
 
   void _event(StreamController controller, data, int index, Element e) {
     if (controller == null) return;
     var rowStr = e.parent.dataset['row'];
     var row = rowStr != null ? int.parse(rowStr) : null;
     controller.add(
         new DefaultChartEventImpl(scope.event, area,
             series, row, series.measures.elementAt(index), data));
   }
 }