Fix text-mode rendering of object and Asana link views

Summary:
Ref T2852. Two issues:

• Embeds (T12, {T12}) have some handle issues because handles run afoul of visibility checks under some configs. Make handles unconditionally visible.
• Asana links don't render correctly into text mode. Give them a valid text mode rendering so they don't flip out.

Test Plan: Made comments with T12 and http://app.asana.com/... and published them to Asana.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T2852

Differential Revision: https://secure.phabricator.com/D6696