Capture events from input elements outside the visualization. Similar to what is done at min 3:19 in the Reactive Vega video
Modified http://vega.github.io/vega-editor/vendor/d3.min.js to a secure url
Modified http://vega.github.io/vega/vega.min.js to a secure url
https://vega.github.io/vega-editor/vendor/d3.min.js
https://vega.github.io/vega/vega.min.js