babel-preset-test-bundled-dependencies/node_modules/core-js/modules/library/_redefine-all.js

Allow custom config for create-react-app without ejecting

var hide = require('./_hide');
module.exports = function(target, src, safe){
  for(var key in src){
    if(safe && target[key])target[key] = src[key];
    else hide(target, key, src[key]);
  } return target;
};