Right now we use codemirror's JavaScript mode on the website but there's a JSX mode now so we should start using that instead.

function split(old) {
      var out = " ";
      for (var i = 0; i < old.length - 2; ++i) out += i % 2 ? " " : "\u00a0";
      out += " ";
      return out;
    }
    return function(builder, text, style, startStyle, endStyle, title) {
      return inner(builder, text.replace(/ {3,}/g, split), style, startStyle, endStyle, title);
    };
  }
  function buildCollapsedSpan(builder, size, marker, ignoreWidget) {