Messages area is rendered when no messages are present.

Problem/Motivation

The gray messages area (as seen in Bartik) is present when no messages are present.

This is a follow-on issue to #2004286: Defer calls to drupal_get_* functions until printed inside a template by adding a RenderWrapper class. The issue was noted in 59f478ff96d31394907f00400d73cb41839237a8 and a git bisect narrowed the regression to #2004286.

Proposed resolution

Not yet known.

Remaining tasks

1. Investigate the cause of the regression.
2. Fix it.