Function makeComparableKey

_benchmarks/sample_echarts.js:7576–7584

* @return return null if not exist.

(val)

    function makeComparableKey(val) {
      if ("development" !== 'production') {
        if (val == null) {
          throw new Error();
        }
      }

      return convertOptionIdName(val, '');
    }

    function convertOptionIdName(idOrName, defaultValue) {
      if (idOrName == null) {