[orca-list] I've removed the checks that prevent Orca's navigation when Gecko content is loading

[Joanmarie Diggs <jdiggs igalia com>]

Hey all.

I've just removed the checks that prevent Orca from processing caret
navigation and structural navigation commands when document content is
loading. This solves issues like not being able to use structural
navigation when downloading files. I don't think removing these checks
will introduce any issues, but if it does, please let me know.

Thanks!
--joanie