Roll Observatory packages and add a roll script

packages/charted/lib/svg/shapes.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
 //
 
 library charted.svg.shapes;
 
 import "dart:html" show Element;
 import "dart:math" as math;
 
 import "package:charted/core/utils.dart";
 import "package:charted/core/interpolators.dart";
 import "package:charted/selection/selection.dart";
 
 part 'shapes/arc.dart';
 part 'shapes/line.dart';
 part 'shapes/area.dart';
 part 'shapes/rect.dart';
 
 /// Common interface provided by all shape implementations.
 abstract class SvgShape {
   /// Generate the path based on the passed data [d], element index [i]
   /// and the element [e].  This method follows the same signature as the
   /// other callbacks used by selection API - [ChartedCallback<String>]
   String path(d, int i, Element e);
 }