Add access modifiers to methods/members in `WP_HTTP_IXR_Client`.

See #27881, #22234.


git-svn-id: https://develop.svn.wordpress.org/trunk@28512 602fd350-edb4-49c9-b593-d223f7449a82
Add missing access modifiers to methods/members in `WP_Image_Editor_*` classes.

See #27881, #22234.


git-svn-id: https://develop.svn.wordpress.org/trunk@28513 602fd350-edb4-49c9-b593-d223f7449a82
Add missing access modifiers to methods/members in `Walker` and subclasses. Add a magic `__get()` method.

See #27881, #22234.


git-svn-id: https://develop.svn.wordpress.org/trunk@28514 602fd350-edb4-49c9-b593-d223f7449a82