Regression: Firefox selection by double click

[k0ka]

Description
Selecting a block in Firefox via double click doesn't allow to remove formatting.

Recording

slateissues.mov

Steps
To reproduce the behavior:

1. Go to https://www.slatejs.org/examples/richtext
2. Double click on a word to select it.
3. Click on the "bold" button.
4. Deselect.
5. Double click on the same word again to select it.
6. Click on the "bold" button.

Expectation
The bold button must be active and the font must get to normal after clicking on the "bold" button again.

Environment

• Slate Version: 0.98.0, 0.98.4, 0.101.0
• Operating System: MacOS, Windows 10
• Browser: Firefox

Context
This bug was reintroduced in slate-react 0.98.0. It was working properly in slate-react 0.97.2

I think it is the same bug as #3336 (or #4793) which was fixed in #5275 and reintroduced in #5486

[tdaron]

+1 with slate version 0.101.1, firefox 120.0, linux

[12joan]

This can be closed as completed: #5580