Bar graph added.

node_modules/vega-canvas/build/vega-canvas.node.js

@@ -0,0 +1,58 @@
+'use strict';
+
+Object.defineProperty(exports, '__esModule', { value: true });
+
+function domCanvas(w, h) {
+  if (typeof document !== 'undefined' && document.createElement) {
+    var c = document.createElement('canvas');
+    if (c && c.getContext) {
+      c.width = w;
+      c.height = h;
+      return c;
+    }
+  }
+  return null;
+}
+
+function domImage() {
+  return typeof Image !== 'undefined' ? Image : null;
+}
+
+var NodeCanvas;
+
+try {
+  NodeCanvas = require('canvas');
+  if (!(NodeCanvas && NodeCanvas.createCanvas)) {
+    NodeCanvas = null;
+  }
+} catch (error) {
+  // do nothing
+}
+
+function nodeCanvas(w, h, type) {
+  if (NodeCanvas) {
+    try {
+      return new NodeCanvas.Canvas(w, h, type);
+    } catch (e) {
+      // do nothing, return null on error
+    }
+  }
+  return null;
+}
+
+function nodeImage() {
+  return (NodeCanvas && NodeCanvas.Image) || null;
+}
+
+function canvas(w, h, type) {
+  return domCanvas(w, h) || nodeCanvas(w, h, type) || null;
+}
+
+function image() {
+  return domImage() || nodeImage() || null;
+}
+
+exports.canvas = canvas;
+exports.domCanvas = domCanvas;
+exports.image = image;
+exports.nodeCanvas = nodeCanvas;