diff -r efd9c589177a -r c0b4a8b5a012 toolkit/javascript/d3/src/core/keys.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/javascript/d3/src/core/keys.js	Thu Apr 10 14:20:23 2014 +0200
@@ -0,0 +1,5 @@
+d3.keys = function(map) {
+  var keys = [];
+  for (var key in map) keys.push(key);
+  return keys;
+};