node_modules/jszip/node_modules/core-js/library/modules/_object-keys.js

// 19.1.2.14 / 15.2.3.14 Object.keys(O)
var $keys       = require('./_object-keys-internal')
  , enumBugKeys = require('./_enum-bug-keys');

module.exports = Object.keys || function keys(O){
  return $keys(O, enumBugKeys);
};