Update dependency webextension-polyfill to v0.9.0

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
webextension-polyfill	0.8.0 -> 0.9.0
@types/webextension-polyfill	0.8.2 -> 0.8.3

---

Release Notes

mozilla/webextension-polyfill

### [`v0.9.0`](https://togithub.com/mozilla/webextension-polyfill/releases/0.9.0) [Compare Source](https://togithub.com/mozilla/webextension-polyfill/compare/0.8.0...0.9.0) ##### Bug Fixes - enable webextension-polyfill usage via webpack ProvidePlugin ([#​351](https://togithub.com/mozilla/webextension-polyfill/issues/351)) See [all changes for 0.9.0](https://togithub.com/mozilla/webextension-polyfill/compare/0.8.0...0.9.0) - https://unpkg.com/webextension-polyfill@0.9.0/dist/

---

Configuration

📅 Schedule: At any time (no schedule defined).

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about these updates again.

---

• [ ] If you want to rebase/retry this PR, click this checkbox.

---

This PR has been generated by WhiteSource Renovate. View repository job log here.