Right, I can go to insert mode, but to leave is, tricky. I found going to replace mode and escape worked in FF. I'm sure its a browser issue, I also have vimium so probably a nightmare of hooks!
Have you tried with <Control-Left Square Bracket>? aka Ctrl-[, or ^[, as seen sometimes in the terminal. This works for me in most terminals as an alternative to Escape when using vi/vim.
In mobile (at least in mine, firefox) the input become buferred autocomplete and when accepted via return, the typed word gets duplicated before entered. Workaround is to accept via space and delete as necessary
