Writing Good Code Is a Lot Like Writing Prose(alexkras.com)

  // Object.values is from ES2017 and Overture uses it; anything that has it will
  // have the other things from ES6 that we need, so we don’t need to add the
  // weight and load time of core-js for them. Browsers that thus need core-js
  // are approximately: IE, Safari≤10.0, iOS≤10.2, Chrome≤53, Firefox≤46,
  // Edge≤13?. No up-to-date browser needs it (for better or for worse).
  if ( !Object.values ) {
      dependencies.O = [ 'core-js' ];
  }

  var needCoreJs = !Object.values;
  if ( needCoreJs ) {
      dependencies.O = [ 'core-js' ];
  }