Provide back compat for $theme->$var where $theme was an array from...

Provide back compat for $theme->$var where $theme was an array from get_themes() but cast to an object, as had occurred in get_theme_updaes(). see #20173. see #20103.

git-svn-id: https://core.svn.wordpress.org/trunk@20112 1a063a9b-81f0-0310-95a4-ce76da25c4cd