Extend from Phobject
Summary: Ensure that all base classes extend from Phobject. See D13275 for some explanation.
Test Plan: arc unit
Reviewers: epriestley, #blessed_reviewers
Reviewed By: epriestley, #blessed_reviewers
Subscribers: epriestley, Korvin
Differential Revision: https://secure.phabricator.com/D13280