Browsing Brazilian Portuguese translation

Translators: Orca has had to implement its own caret navigation model to work
around issues in Gecko/Firefox. In some versions of Firefox, we must perform
a focus grab on each object being navigated in order for things to work as
expected; in other versions of Firefox, we must avoid doing so in order for
things# to work as expected. We cannot identify with certainty which situation
the user is in, so we must provide this as an option within Orca.