This is the first time I have seen this kind of problem.
This isn't a problem, it's just an extra feature/option provided by the browser OP is using. You get the same dialogue if you are using Chrome but without the option to disable JavaScript dialogues until the next browser launch.
This has happened several times, which is likely due to a browser bug.
Several times? Where? Can you please show us? And, how can a bug create a checkbox followed by a logical question in a dialogue box?
You can clear the data and try again, and it will be resolved.
As I said above, it's not a problem that needs to be solved, it is just an extra option provided by the browser being used, probably, and clearing the data won't make a difference here.
If it is you still need to fix it, you can message support to find out what problem it is causing.