issues when using backspace key to remove image in Firefox

[waiho]

In firefox, backspace key is shortcut key for 'go back one page'.
Steps to reproduce the issue

1. using Firefox to go to any web page first, so that browser has previous page to go back.
2. use the same browser window to open a page, e.g (https://codesandbox.io/s/4wnwllnnl9) which has quill-blot-formatter to insert image,
3. click on the image to select it.
4. use 'backspace' key to remove the image
   Expected: image is being removed
   Problem: the browser goes back to previous web page