Update Rollup to use HMR with Sapper

src/client.js

@@ -1,5 +1,6 @@
 import * as sapper from '@sapper/app'
 
+// Start Sapper
 sapper.start({
 	target: document.getElementById('site')
 })

src/server.js

@@ -3,10 +3,12 @@ import polka from 'polka'
 import compression from 'compression'
 import * as sapper from '@sapper/server'
 
+// Define environment
 const { PORT, NODE_ENV } = process.env
 const dev = NODE_ENV === 'development'
 
-polka() // You can also use Express
+// Setup server
+polka()
 	.use(
 		compression({ threshold: 0 }),
 		sirv('static', { dev }),

src/service-worker.js

@@ -7,6 +7,7 @@ const ASSETS = `cache${timestamp}`
 const to_cache = shell.concat(files)
 const cached = new Set(to_cache)
 
+// Install
 self.addEventListener('install', event => {
 	event.waitUntil(
 		caches
@@ -18,6 +19,7 @@ self.addEventListener('install', event => {
 	)
 })
 
+// Activate
 self.addEventListener('activate', event => {
 	event.waitUntil(
 		caches.keys().then(async keys => {
@@ -31,6 +33,7 @@ self.addEventListener('activate', event => {
 	)
 })
 
+// Fetch
 self.addEventListener('fetch', event => {
 	if (event.request.method !== 'GET' || event.request.headers.has('range')) return