Fix comment anchor jump highlighting

Summary: I accidentally broke the feature where we highlight comments which are
jumped to via anchor in D1327. We now test that the jump was sucessful by
looking for an item with the anchor ID, but we were only setting 'name'.
Instead, set 'id' as well so the highlighting code detects that the jump was
successful and adds the highlight class.

Test Plan: Clicked "Comment D1234#7" or whatever, got a nice yellow background.

Reviewers: btrahan, nh, jungejason

Reviewed By: btrahan

CC: aran, epriestley

Maniphest Tasks: T796

Differential Revision: https://secure.phabricator.com/D1471