Roll Observatory packages and add a roll script

packages/charted/examples/charts/renderers/demo_pie_charts.dart

+
+library charted.demo.charts.bar_charts;
+
+import "dart:html";
+import "package:charted/charts/charts.dart";
+import "../demo_charts.dart";
+
+void drawSimplePieChart(String selector, bool isDonut) {
+  var wrapper = document.querySelector(selector),
+      areaHost = wrapper.querySelector('.chart-host'),
+      legendHost = wrapper.querySelector('.chart-legend-host');
+
+  var series = new ChartSeries("one", [2],
+          new PieChartRenderer(innerRadiusRatio: isDonut ? 0.618 : 0)),
+      config = new ChartConfig([series], [0])
+        ..legend = new ChartLegend(legendHost, showValues: true),
+      data = new ChartData(ORDINAL_DATA_COLUMNS, ORDINAL_DATA),
+      state = new ChartState();
+
+  var area = new LayoutArea(areaHost, data, config, state: state);
+
+  createDefaultCartesianBehaviors().forEach((behavior) {
+    area.addChartBehavior(behavior);
+  });
+  area.draw();
+}
+
+void drawPieChartWithCount(String selector, bool isDonut, int count) {
+  var wrapper = document.querySelector(selector),
+      areaHost = wrapper.querySelector('.chart-host'),
+      legendHost = wrapper.querySelector('.chart-legend-host');
+
+  var series = new ChartSeries("one", [2],
+          new PieChartRenderer(
+              innerRadiusRatio: isDonut ? 0.618 : 0, maxSliceCount: count)),
+      config = new ChartConfig([series], [0])
+        ..legend = new ChartLegend(legendHost, showValues: true),
+      data = new ChartData(ORDINAL_DATA_COLUMNS, ORDINAL_DATA),
+      state = new ChartState();
+
+  var area = new LayoutArea(areaHost, data, config, state: state);
+
+  createDefaultCartesianBehaviors().forEach((behavior) {
+    area.addChartBehavior(behavior);
+  });
+  area.draw();
+}
+
+main() {
+  drawSimplePieChart('#simple-pie-chart', false);
+  drawSimplePieChart('#simple-donut-chart', true);
+  drawPieChartWithCount('#pie-chart-with-count', false, 5);
+  drawPieChartWithCount('#donut-chart-with-count', true, 5);
+}
+