[#140382397] #3 fix karma testing for ES6

.tmp/mocha-webpack/455fffbb3125fc1ebc427c559e4e5438-entry.js

...427c559e4e5438/455fffbb3125fc1ebc427c559e4e5438-output.js

assets/js/__test__/FormLogin-test.jsx

assets/js/__test__/server-test.jsx

assets/js/components/FormLogin.jsx

karma.conf.js

package.json

tests.webpack.js

webpack.config.js