Checkboxes "All of the above" option - broken UI

Hello,

We discovered the problem with "All of the above" checkbox option.
The problem shows up after webform submission and the page reload - checked checkboxes are not checked in the UI.
It happens because of JS file for this special option (webform/js/webform.element.checkboxes.js) - on page load checkboxes are checked but after script execution it unchecks all checkboxes.

Steps to reproduce:
- Create webform with checkboxes and "All of the above" option
- Fill out the form (click check all checkbox)
- Submit
(if checked checkboxes are still there refresh the page)
- On page load we can see checked checkoxes (less than 1s)
- Checkboxes are unchecked (on dev tools we can see that checkboxes have checked attribute - except "All of the above" checkbox)

Thanks,
Pierre