The Robinson projection is available as d3.geo.robinson
in the geo.projection plugin.
Changed /mbostock/raw/4090846/world-50m.json to a local referenece
https://d3js.org/d3.v3.min.js
https://d3js.org/d3.geo.projection.v0.min.js
https://d3js.org/topojson.v1.min.js