Fix global process testing for the process polyfill (#33220)

When there is a DOM element with id of `process`, the DOM marks it as a global, so `window.process` would exist. We should check for `process.env` to make sure it is available too.

packages/next/build/polyfills/process.js

@@ -1 +1,4 @@
-module.exports = global.process || require('../../compiled/process')
+module.exports =
+  global.process?.env && typeof global.process?.env === 'object'
+    ? global.process
+    : require('../../compiled/process')

test/integration/polyfills/pages/process.js

@@ -0,0 +1,7 @@
+export default function Page() {
+  return (
+    <div id="process">
+      Hello, {process.env.NEXT_PUBLIC_VISITOR ?? 'stranger'}
+    </div>
+  )
+}

test/integration/polyfills/test/index.test.js

@@ -36,9 +36,18 @@ describe('Polyfills', () => {
     await browser.close()
   })
 
+  it('should allow using process.env when there is an element with `id` of `process`', async () => {
+    const browser = await webdriver(appPort, '/process')
+    const text = await browser.elementByCss('#process').text()
+
+    expect(text).toBe('Hello, stranger')
+
+    await browser.close()
+  })
+
   it('should contain generated page count in output', async () => {
-    expect(output).toContain('Generating static pages (0/4)')
-    expect(output).toContain('Generating static pages (4/4)')
+    expect(output).toContain('Generating static pages (0/5)')
+    expect(output).toContain('Generating static pages (5/5)')
     // we should only have 1 segment and the initial message logged out
     expect(output.match(/Generating static pages/g).length).toBe(5)
   })