fix(worker): fix importScripts injection breaking iife code

.prettierignore

@@ -11,3 +11,4 @@ playground/html/invalid.html
 playground/html/valid.html
 playground/external/public/[email protected]
 playground/ssr-html/public/[email protected]
+playground/worker/classic-iife.js

packages/vite/src/node/plugins/worker.ts

@@ -265,7 +265,7 @@ export function webWorkerPlugin(config: ResolvedConfig): Plugin {
         }
         if (injectEnv) {
           const s = new MagicString(raw)
-          s.prepend(injectEnv)
+          s.prepend(injectEnv + ';\n')
           return {
             code: s.toString(),
             map: s.generateMap({ hires: 'boundary' }),

playground/worker/__tests__/es/worker-es.spec.ts

@@ -190,6 +190,11 @@ test('classic worker', async () => {
     'A classic',
     true,
   )
+  await untilUpdated(
+    () => page.textContent('.classic-iife'),
+    'classic-iife',
+    true,
+  )
 })
 
 test('emit chunk', async () => {

playground/worker/classic-iife.js

@@ -0,0 +1,5 @@
+(() => {
+  self.addEventListener('message', () => {
+    self.postMessage('classic-iife');
+  })
+})()

playground/worker/index.html

@@ -132,6 +132,7 @@ <h2 class="format-iife">format iife:</h2>
 </p>
 <code class="classic-worker"></code>
 <code class="classic-worker-import"></code>
+<code class="classic-iife"></code>
 
 <p>
   new SharedWorker(new URL('./classic-shared-worker.js', import.meta.url), {

playground/worker/worker/main-classic.js

@@ -38,3 +38,9 @@ classicSharedWorker.port.addEventListener('message', (ev) => {
   text('.classic-shared-worker', JSON.stringify(ev.data))
 })
 classicSharedWorker.port.start()
+
+const classicIife = new Worker(new URL('../classic-iife.js', import.meta.url))
+classicIife.addEventListener('message', (e) => {
+  text('.classic-iife', e.data)
+})
+classicIife.postMessage('ping')