"At a Glance" widget: Move `get_avatar()` line out of if-block.

This allows you to show avatars for custom comment types via the `get_avatar_comment_types` filter.

props zodiac1978.
fixes #26944.
Built from https://develop.svn.wordpress.org/trunk@27384


git-svn-id: http://core.svn.wordpress.org/trunk@27232 1a063a9b-81f0-0310-95a4-ce76da25c4cd