1.31.2

[Commits to master since this release](https://github.com/gorhill/uBlock/compare/1.31.2...master)
[Commits since last release](https://github.com/gorhill/uBlock/compare/1.31.0...1.31.2)

To install the stable build:

- **Firefox**: Will not be submitted <!-- Click [uBlock0_1.31.0.firefox.signed.xpi](https://addons.mozilla.org/firefox/downloads/file/3679754/ublock_origin-1.31.0-an+fx.xpi) -->
    - uBO works best on Firefox.
- **Chromium**: Install from the Chrome store (CWS): <https://chrome.google.com/webstore/detail/ublock-origin/cjpalhdlnbpafiamejdnhcphjbkeiagm>
    - For Chromium version 54 and older, it is necessary to enable "Experimental JavaScript" at `chrome://flags/#enable-javascript-harmony`.
- **Edge**: Install from Microsoft Store: <https://microsoftedge.microsoft.com/addons/detail/odfafepnkmbhccpbejgmiehpchacaeak>
    - The Microsoft Store version of uBO is published by [Nik Rolls](https://github.com/nikrolls/uBlock-Edge)
- **Opera**: Install from Opera addons: <https://addons.opera.com/en/extensions/details/ublock/>

---

This minor release benefits Chromium-based browsers. Chromium 87 added the long time missing [`tabs.removeCSS()` API](https://developer.chrome.com/extensions/tabs#method-removeCSS), which uBO uses:

- To enable the real-time toggling of cosmetic filters through the [no-cosmetic-filtering switch](https://github.com/gorhill/uBlock/wiki/Per-site-switches#no-cosmetic-filtering);
- To enable visualization of hidden elements in [DOM inspector](https://github.com/gorhill/uBlock/wiki/DOM-inspector).

But the call to `tabs.removeCSS()` was still failing in uBO due to Chromium being more strict regarding the arguments passed to the API.

## Closed as fixed:

- [tabs.removeCSS does not work as expected in Chromium 87](https://github.com/uBlockOrigin/uBlock-issues/issues/1375)

## Commit with no entry in issue tracker:

- [Fix handling of no-longer-existing port condition](https://github.com/gorhill/uBlock/commit/4d68d7f586bab3c692f6648c4af7fd49e8dff395)