Undo/redo on block contextualizations creation/deletion does not work in Firefox

[robindemourat]

To Reproduce Steps to reproduce the behavior:

1. dnd an image to the editor
2. focus on the editor
3. hit cmd+z

Other related scenario :

1. delete an image in the editor
2. hit cmd+z

Desktop (please complete the following information):

• OS: iOs
• Browser firefox
• Version 62

Additional context Add any other context about the problem here.

[robindemourat]

Update : still there