Use runtime caching for .js and .html files.

generator/src/develop.js

@@ -191,7 +191,7 @@ function webpackOptions(production, routes, { debug, manifestConfig }) {
       }),
       new InjectManifest({
         swSrc: path.resolve(__dirname, "./service-worker-template.js"),
-        include: [/^index\.html$/, /\.js$/, /\.(?:png|gif|jpg|jpeg|svg)$/],
+        include: [],
         exclude: [
           /android-chrome-.*\.png$/,
           /apple-touch-icon.*\.png/,

generator/src/service-worker-template.js

@@ -14,6 +14,14 @@ workbox.routing.registerRoute(
   }),
   "GET"
 );
+workbox.routing.registerRoute(
+  /(^index\.html$|.js$)/,
+  new workbox.strategies.NetworkFirst({
+    cacheName: "shell",
+    plugins: []
+  }),
+  "GET"
+);
 workbox.routing.registerRoute(
   /^https:\/\/fonts\.googleapis\.com/,
   new workbox.strategies.StaleWhileRevalidate({