Restrict aprhont-form-width to certain input types

Summary: Fixes T11491, I believe these are the only two that need to be specified.

Test Plan: Checked Create pages for diffs, tasks, projects, events, blogs, login, etc. Mobile/Desktop.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T11491

Differential Revision: https://secure.phabricator.com/D16416