R1:992dedcadd20

Modernize Differential SearchEngine just enough to get NUX

Summary: Ref T10032. This is sufficent to hit NUX without doing anything bad.

Test Plan:
- Visited NUX.
- Browsed normally.

{F1043191}

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10032

Differential Revision: https://secure.phabricator.com/D14876