Use correct method name in Harbormaster UI event listener
Summary: See thread; fixes fatal. The actual name of this method is getHarbormaster....
NOTE: This fixes a fatal in Differential which impedes review, so I'm pushing it as-is.
Test Plan: Browsed a revision.
Reviewers: btrahan
CC: aran
Differential Revision: https://secure.phabricator.com/D7834