fix failed to update points in doughnut chart

Author: neoalienson

lib/core.js

@@ -85,7 +85,7 @@ var dataKeys = {
 var updatePoints = function(nextProps, chart) {
   var name = chart.name;
 
-  if (name === 'PolarArea' || name === 'Pie') {
+  if (name === 'PolarArea' || name === 'Pie' || name === 'Doughnut') {
     nextProps.data.forEach(function(segment, segmentIndex) {
       chart.segments[segmentIndex].value = segment.value;
     });