I'd go for something like
/* TranslateServices.php */
public static function wrap( MediaWikiServices $services ) { return new
self( $services ); }
/* ServiceWiring.php */
'Translate:TranslatablePageParser' => function ( MediaWikiServices
$services ) {
return new TranslatablePageParser(
TranslateServices::wrap( $services
)->getParsingPlaceholderFactory();
};
},