Use textContent instead of innerHTML for linking symbols

Summary: Go to https://secure.phabricator.com/D2646#59cc9d49 and click on array_mergev to repro.

Test Plan: Checked if the property exists in DOM inspector.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D2742