Fix a bad parameter read in hovercard

Summary: I broke this at the last second in D17374. getStrList() doesn't read arrays. It probably should (more modern analogs do) but don't rock the boat in the leadup to the release cut.

Test Plan: Hovered over a thing, saw a hovercard and no getStrList() error in my logs.

Reviewers: chad

Reviewed By: chad

Differential Revision: https://secure.phabricator.com/D17383