Fix Service Worker matching external top-level URLs

At the moment the Service Worker matches any external top-level path (e.g. https://any.external.domain.com/?query_params) as a home url, as `isHomeRoute` makes a mere string equality check against `url.pathname`.

I stumbled upon these while trying to load the script for Zendesk Chat, whose URL has the form `https://v2.zopim.com/?APP_KEY_HASH`.

This commit introduces an additional check to make sure that the URL origin matches the service worker origin, too, just as it would happen when passing a `RegExp` (bc of additional assumptions of workbox on the use of `RegExp`s that only make them match on local URLS)

packages/venia-concept/src/ServiceWorker/registerRoutes.js

@@ -83,7 +83,7 @@ export default function() {
      * and the cycle repeats.
      */
     registerRoute(
-        ({ url }) => isHTMLRoute(url),
+        ({ url }) => (url.origin === self.location.origin) && isHTMLRoute(url),
         new StaleWhileRevalidate({
             plugins: [
                 {