Disappeared URL-icons in context menu "Undo Close Tab" extension

### Describe the bug

After update 8.7.2 -> 8.7.4 (Lepton-Photon-Style) disappeared URL-icons in context menu "Undo Close Tab" extension (https://addons.mozilla.org/ru/firefox/addon/undoclosetabbutton/).

### Expected behavior

Return behavior like in previous 8.7.2 version.

### Screenshots

### OS

Windows 10

### OS - Others

_No response_

### Firefox Version

Firefox 140.5.0esr

### Distribution

- [ ] [Original Lepton](https://github.com/black7375/Firefox-UI-Fix)
- [x] [Lepton's photon style](https://github.com/black7375/Firefox-UI-Fix/tree/photon-style)
- [ ] [Lepton's proton style](https://github.com/black7375/Firefox-UI-Fix/tree/proton-style)

### Theme

- [ ] Light
- [ ] Dark
- [ ] Alpenglow (System: Light)
- [ ] Alpenglow (System: Dark)
- [ ] System Default
- [ ] Others: (e.g. [Photon Colors](https://addons.mozilla.org/en-US/firefox/addon/photon-colors/), [Google Chrome Dark](https://addons.mozilla.org/en-US/firefox/addon/google-chrome-dark/), [Fairytale Of Nature](https://addons.mozilla.org/en-US/firefox/addon/fairytale-of-nature/))

### Theme - More Info

_No response_

### `user.js` setup

user.js setup

```javascript
// Your settings
```

### Additional context

_No response_

Reproduce the missing URL icons in the Undo Close Tab extension context menu on Firefox 140.5.0esr using the Lepton photon-style branch, then compare the result with version 8.7.2 and the supplied screenshots. Trace the SCSS rules affecting that menu and verify that the icons return without regressing the updated 8.7.4 appearance.

Written by the indexing model from the issue text.