Added private-methods

[mansoor-omrani]

private-methods were missed from the TC39 list

[netlify[bot]]

✅ Deploy Preview for babel ready!

Built without sensitive environment variables

Name	Link
🔨 Latest commit	4a3e03935dea412cbfc932004966f2375779002a
🔍 Latest deploy log	https://app.netlify.com/sites/babel/deploys/633babe7fb9d6800081fc2f6
😎 Deploy Preview	https://deploy-preview-2690--babel.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site settings.

[liuxingbaoyu]

Thanks!