R1:90064a350a02

Fix URI construction of typeahead browse "more" pager

Summary: Ref T13251. See <https://phabricator.wikimedia.org/T216849>.

Test Plan:
- With more than 100 projects (or, set `$limit = 3`)...
- Edit a task, then click the "Browse" magnifying glass icon next to the "Tags" typeahead.
- Before change: fatal on 'q' being null.
- After change: no fatal.

Reviewers: amckinley, 20after4

Reviewed By: amckinley

Maniphest Tasks: T13251

Differential Revision: https://secure.phabricator.com/D20204