Repent for our original OOP sins and doc blocks as pertains to access modifiers in List Table + subclasses.

Props SergeyBiryukov.
See #28843 and [28583].

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The 2nd argument to `array_unique()` was added to PHP in 5.2.9, so don't use it. We have to use our own code to return unique terms when `fields => all` in `wp_get_object_terms()`.

See #28843 and [28583].

Built from https://develop.svn.wordpress.org/trunk@29119


git-svn-id: http://core.svn.wordpress.org/trunk@28905 1a063a9b-81f0-0310-95a4-ce76da25c4cd