Improve `gi` text selection

Improve `gi` text selection

Before you have focused a text input (a prevented autofocus does _not_ count),
`gi` now selects all text in the text input it focuses (before, it only did so
for inputs that had autofocus prevented). The reason is that many sites prefill
search boxes with your query on search results pages. Then it’s nice if `gi`
selects all the text, letting you quickly replace it.

This is a continuation of commit b3e8a037.