Roll Observatory packages and add a roll script

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

Index: packages/charted/examples/charts/renderers/demo_combo_charts.dart
diff --git a/packages/charted/examples/charts/renderers/demo_combo_charts.dart b/packages/charted/examples/charts/renderers/demo_combo_charts.dart
new file mode 100644
index 0000000000000000000000000000000000000000..9a0a2211f2e1cf2f22513b3ed1b30c92d3814a7f
--- /dev/null
+++ b/packages/charted/examples/charts/renderers/demo_combo_charts.dart
@@ -0,0 +1,56 @@
+
+library charted.demo.charts.combo_charts;
+
+import "dart:html";
+import "package:charted/charts/charts.dart";
+import "../demo_charts.dart";
+
+void drawBarLineCombo(String selector, bool grouped) {
+  var wrapper = document.querySelector(selector),
+      areaHost = wrapper.querySelector('.chart-host'),
+      legendHost = wrapper.querySelector('.chart-legend-host');
+
+  var series1 = new ChartSeries(
+          "one", grouped ? [2, 3] : [2], new BarChartRenderer()),
+      series2 = new ChartSeries("two", [1], new LineChartRenderer()),
+      config = new ChartConfig([series1, series2], [0])
+        ..legend = new ChartLegend(legendHost),
+      data = new ChartData(
+          ORDINAL_DATA_COLUMNS, ORDINAL_DATA),
+      state = new ChartState();
+
+  var area = new CartesianArea(areaHost, data, config, state: state);
+
+  createDefaultCartesianBehaviors().forEach((behavior) {
+    area.addChartBehavior(behavior);
+  });
+  area.draw();
+}
+
+void drawStackedBarLineCombo(String selector) {
+  var wrapper = document.querySelector(selector),
+      areaHost = wrapper.querySelector('.chart-host'),
+      legendHost = wrapper.querySelector('.chart-legend-host');
+
+  var series1 = new ChartSeries(
+          "one", [2, 3], new StackedBarChartRenderer()),
+      series2 = new ChartSeries("two", [1], new LineChartRenderer()),
+      config = new ChartConfig([series1, series2], [0])
+        ..legend = new ChartLegend(legendHost),
+      data = new ChartData(
+          ORDINAL_DATA_COLUMNS, ORDINAL_DATA),
+      state = new ChartState();
+
+  var area = new CartesianArea(areaHost, data, config, state: state);
+
+  createDefaultCartesianBehaviors().forEach((behavior) {
+    area.addChartBehavior(behavior);
+  });
+  area.draw();
+}
+
+main() {
+  drawBarLineCombo('#bar-line-combo-chart', false);
+  drawBarLineCombo('#grouped-bar-line-combo-chart', true);
+  drawStackedBarLineCombo('#stacked-bar-line-combo-chart');
+}