Fx52+: URL with space lead to search

[pintassilgo]

example.com/?query=foo bar

Cause:
https://hg.mozilla.org/integration/autoland/rev/bb8d2847640f

[pintassilgo]

Seems that insert
if (popup.richlistbox.children[targetIndex].getAttribute('type') !== 'searchengine')
before /lib/main.js line 121
popup.selectedIndex = targetIndex;
fixes this issue.