[DevTools] Use documentElement to override cmd+F (#34734)

We override Cmd+F to jump to our search input instead of searching
through the HTML. This is ofc critical since our view virtualized.

However, Chrome DevTools installs its own listener on the document as
well (in the bubble phase) so if we prevent it at the document level
it's too late and it ends up stealing the focus instead. If we instead
listen at the documentElement it works as intended.