Update ESLint for Code Climate (#7696)

* Update babel-eslint to version 8.2.3

* Update eslint to version 4.19.1

* Update eslint-plugin-promise to version 3.8.0

* Update eslint-plugin-react to version 7.8.2

* Upgrade eslint-plugin-jsx-a11y to version 6.0.3

* yarn test:lint --fix

app/javascript/mastodon/service_worker/entry.js

@@ -33,7 +33,7 @@ self.addEventListener('fetch', function(event) {
 
     event.respondWith(asyncResponse.then(
       response => asyncCache.then(cache => cache.put('/', response.clone()))
-                            .then(() => response),
+        .then(() => response),
       () => asyncCache.then(cache => cache.match('/'))));
   } else if (url.pathname === '/auth/sign_out') {
     const asyncResponse = fetch(event.request);