freifunk-app/node_modules/core-js/library/modules/$.enum-keys.js

// all enumerable object keys, includes symbols
var $ = require('./$');
module.exports = function(it){
  var keys       = $.getKeys(it)
    , getSymbols = $.getSymbols;
  if(getSymbols){
    var symbols = getSymbols(it)
      , isEnum  = $.isEnum
      , i       = 0
      , key;
    while(symbols.length > i)if(isEnum.call(it, key = symbols[i++]))keys.push(key);
  }
  return keys;
};