Convert AphrontErrorView to safe HTML
Summary: Done by searching for AphrontErrorView and then appendChild().
Test Plan:
Looked at Commit Detail.
Looked at Revision Detail.
Reviewers: epriestley
Reviewed By: epriestley
CC: aran, Korvin
Maniphest Tasks: T2432
Differential Revision: https://secure.phabricator.com/D4843