Roll Observatory packages and add a roll script

packages/charted/lib/charts/layout_renderers/pie_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 162 matching lines @@
     root.selectAll('.pie-path').remove();
   }
 
   void _event(StreamController controller, data, int index, Element e) {
     // Currently, events are not supported on "Other" pie
     if (controller == null || data.data == SMALL_INT_MAX) return;
     controller.add(new DefaultChartEventImpl(
          scope.event, area, series, data.data, series.measures.first, data.value));
   }
 }