Have Browse button in History actually work

Summary: Ref T12780. Makes the button do something useful, like link to the history at the right spot in the graph.

Test Plan: Click on various browse buttons, get correct url.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T12780

Differential Revision: https://secure.phabricator.com/D18054