feat(firefox): bump to 1221 (#4656)

Author: dgozman

README.md

@@ -1,6 +1,6 @@
 # 🎭 Playwright
 
-[![npm version](https://img.shields.io/npm/v/playwright.svg?style=flat)](https://www.npmjs.com/package/playwright) [![Join Slack](https://img.shields.io/badge/join-slack-infomational)](https://join.slack.com/t/playwright/shared_invite/enQtOTEyMTUxMzgxMjIwLThjMDUxZmIyNTRiMTJjNjIyMzdmZDA3MTQxZWUwZTFjZjQwNGYxZGM5MzRmNzZlMWI5ZWUyOTkzMjE5Njg1NDg) <!-- GEN:chromium-version-badge -->[![Chromium version](https://img.shields.io/badge/chromium-89.0.4344.0-blue.svg?logo=google-chrome)](https://www.chromium.org/Home)<!-- GEN:stop --> <!-- GEN:firefox-version-badge -->[![Firefox version](https://img.shields.io/badge/firefox-84.0b7-blue.svg?logo=mozilla-firefox)](https://www.mozilla.org/en-US/firefox/new/)<!-- GEN:stop --> [![WebKit version](https://img.shields.io/badge/webkit-14.0-blue.svg?logo=safari)](https://webkit.org/)
+[![npm version](https://img.shields.io/npm/v/playwright.svg?style=flat)](https://www.npmjs.com/package/playwright) [![Join Slack](https://img.shields.io/badge/join-slack-infomational)](https://join.slack.com/t/playwright/shared_invite/enQtOTEyMTUxMzgxMjIwLThjMDUxZmIyNTRiMTJjNjIyMzdmZDA3MTQxZWUwZTFjZjQwNGYxZGM5MzRmNzZlMWI5ZWUyOTkzMjE5Njg1NDg) <!-- GEN:chromium-version-badge -->[![Chromium version](https://img.shields.io/badge/chromium-89.0.4344.0-blue.svg?logo=google-chrome)](https://www.chromium.org/Home)<!-- GEN:stop --> <!-- GEN:firefox-version-badge -->[![Firefox version](https://img.shields.io/badge/firefox-84.0b9-blue.svg?logo=mozilla-firefox)](https://www.mozilla.org/en-US/firefox/new/)<!-- GEN:stop --> [![WebKit version](https://img.shields.io/badge/webkit-14.0-blue.svg?logo=safari)](https://webkit.org/)
 
 ## [Documentation](https://playwright.dev) | [API reference](https://playwright.dev/#?path=docs/api.md)
 
@@ -10,7 +10,7 @@ Playwright is a Node.js library to automate [Chromium](https://www.chromium.org/
 |   :---   | :---: | :---: | :---:   |
 | Chromium <!-- GEN:chromium-version -->89.0.4344.0<!-- GEN:stop --> | :white_check_mark: | :white_check_mark: | :white_check_mark: |
 | WebKit 14.1 | :white_check_mark: | :white_check_mark: | :white_check_mark: |
-| Firefox <!-- GEN:firefox-version -->84.0b7<!-- GEN:stop --> | :white_check_mark: | :white_check_mark: | :white_check_mark: |
+| Firefox <!-- GEN:firefox-version -->84.0b9<!-- GEN:stop --> | :white_check_mark: | :white_check_mark: | :white_check_mark: |
 
 Headless execution is supported for all the browsers on all platforms. Check out [system requirements](https://playwright.dev/#?path=docs/intro.md&q=system-requirements) for details.
 

browsers.json

@@ -8,7 +8,7 @@
     },
     {
       "name": "firefox",
-      "revision": "1218",
+      "revision": "1221",
       "download": true
     },
     {