WP_JSON_Base_Posts_Controller should extend WP_JSON_Controller.
Fix indentation in WP_JSON_Base_Posts_Controller::create_item method.
Move get_item_revisions method into the base post class.
Rename check_edit_permission method to check_update_permission
Rename test method to match controller method names.
Remove duplicate placeholder method that now exists in parent.
Return WP_Error if revisions are not supported by given post.
Return empty string instead of null for empty excerpts.
Use post_type property to confirm type isn't being changed on update