Background Updates: Fix a PHP Warning caused by a Upgrader instance being passed into the Theme & Plugin $extra_stats parameter.
Background Updates: Fix two variable typos in r27905

Merges [27906], [27928] to the 3.8 branch.
Fixes #27633.

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git-svn-id: http://core.svn.wordpress.org/branches/3.8@27759 1a063a9b-81f0-0310-95a4-ce76da25c4cd