re-add registerServerWorker

src/registerServiceWorker.js

@@ -21,13 +21,13 @@ const isLocalhost = Boolean(
 export default function register() {
   if (process.env.NODE_ENV === 'production' && 'serviceWorker' in navigator) {
     // The URL constructor is available in all browsers that support SW.
-    // const publicUrl = new URL(process.env.PUBLIC_URL, window.location);
+    const publicUrl = new URL(process.env.PUBLIC_URL, window.location);
-    // if (publicUrl.origin !== window.location.origin) {
+    if (publicUrl.origin !== window.location.origin) {
-    //   // Our service worker won't work if PUBLIC_URL is on a different origin
+      // Our service worker won't work if PUBLIC_URL is on a different origin
-    //   // from what our page is served on. This might happen if a CDN is used to
+      // from what our page is served on. This might happen if a CDN is used to
-    //   // serve assets; see https://github.com/facebookincubator/create-react-app/issues/2374
+      // serve assets; see https://github.com/facebookincubator/create-react-app/issues/2374
-    //   return;
+      return;
-    // }
+    }
 
     window.addEventListener('load', () => {
       const swUrl = `${process.env.PUBLIC_URL}/service-worker.js`;