These lines were introduced in 612f59aa10eef2bf6559deddfb54b84a0a30c6bc
when the only shortcuts were +/-/=/0 (to change zoom level).
Back then, when the input fields were focused, using these keys would
add these unwanted characters to the input field and change the zoom
level of the viewer. Having both operations at the same time was an
undesired event, so a check was inserted, to ignore shortcuts when
the toolbar is focused.
The #toolbar element doesn't exist any more, so these lines are obsolete.
64a4a27455