Backspace doesn't work at the host key confirm prompt

I've only added 2 hosts to blink and since I'm apparently unable to type reliably on the Smart Keyboard I managed to typo the "yes" to the prompt to add the host key both times.

Unfortunately, backspace seems not to work at that prompt.

Reproduce the host key confirmation prompt in Blink on iOS using the Smart Keyboard, then trace how prompt input handles editing. Confirm the fix by checking that Backspace removes a typo before submission and that the corrected response can still be accepted.

Written by the indexing model from the issue text.