Reduce loudness of Inline Comments

Summary: Initially the intent was to mimic the property list headers but in practice this wasn't really needed. Reduced the caps and font weight. Left the icon for easy deliniation.

Test Plan:
Review inline comments before and after change

{F149749}

{F149750}

Reviewers: btrahan, epriestley

Reviewed By: epriestley

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D8936