Some classes with `__get()` method also need `__set()`.

See #27881, #22234.


git-svn-id: https://develop.svn.wordpress.org/trunk@28521 602fd350-edb4-49c9-b593-d223f7449a82
Add missing access modifiers to methods in `WP_Meta_Query`.

See #27881, #22234.


git-svn-id: https://develop.svn.wordpress.org/trunk@28522 602fd350-edb4-49c9-b593-d223f7449a82