cherry-pick(#34530): fix(firefox): disable fetch keep-alive for now before a proper fix (#34534)

Co-authored-by: Andrey Lushnikov <[email protected]>

Author: dgozman

packages/playwright-core/src/server/firefox/ffBrowser.ts

@@ -435,4 +435,6 @@ function toJugglerProxyOptions(proxy: types.ProxySettings) {
 
 // Prefs for quick fixes that didn't make it to the build.
 // Should all be moved to `playwright.cfg`.
-const kBandaidFirefoxUserPrefs = {};
+const kBandaidFirefoxUserPrefs = {
+  'dom.fetchKeepalive.enabled': false,
+};

tests/page/page-event-request.spec.ts

@@ -41,6 +41,19 @@ it('should fire for fetches', async ({ page, server }) => {
   expect(requests.length).toBe(2);
 });
 
+it('should fire for fetches with keepalive: true', {
+  annotation: {
+    type: 'issue',
+    description: 'https://github.com/microsoft/playwright/issues/34497'
+  }
+}, async ({ page, server, browserName }) => {
+  const requests = [];
+  page.on('request', request => requests.push(request));
+  await page.goto(server.EMPTY_PAGE);
+  await page.evaluate(() => fetch('/empty.html', { keepalive: true }));
+  expect(requests.length).toBe(2);
+});
+
 it('should report requests and responses handled by service worker', async ({ page, server, isAndroid, isElectron }) => {
   it.fixme(isAndroid);
   it.fixme(isElectron);