R1:c5a734073d24

Fix two global search issues

Summary:
Fixes T8016.

- Don't explode on bad UTF8, if we happen to get some for whatever reason.
- Don't put `<strong>` tags in the "title" attribute.

Test Plan: Faked bad UTF8, no fatal. Hovered titles, no `<strong>` tags.

Reviewers: btrahan, chad

Reviewed By: chad

Subscribers: epriestley

Maniphest Tasks: T8016

Differential Revision: https://secure.phabricator.com/D12710