diff -r efd9c589177a -r c0b4a8b5a012 toolkit/javascript/d3/src/core/round.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/javascript/d3/src/core/round.js	Thu Apr 10 14:20:23 2014 +0200
@@ -0,0 +1,5 @@
+d3.round = function(x, n) {
+  return n
+      ? Math.round(x * Math.pow(10, n)) * Math.pow(10, -n)
+      : Math.round(x);
+};