Merge pull request #1 from plotly/es6-import

Fix d3v3 ES6 import

Author: archmoj

d3.js

@@ -9556,4 +9556,4 @@
     return request.responseXML;
   });
   if (typeof define === "function" && define.amd) this.d3 = d3, define(d3); else if (typeof module === "object" && module.exports) module.exports = d3; else this.d3 = d3;
-}();
+}.apply(self);