Use an empty array instead of the uls-p-lang-dummy list item (PHP)

This change avoids a flash of a list item bullet while loading on skin
MonoBook.

The JavaScript part of this change is in
Id7f429d9d1217316341102e27389711525f17b2d. The JavaScript part should get
deployed when the HTML caches of this change has expired.

Change-Id: I54a18f5bd85a8261a25e1160dda7a33fbdf3dd7b

UniversalLanguageSelector.hooks.php

@@ -434,12 +434,10 @@ class UniversalLanguageSelectorHooks {
 			return true;
 		}
 
-		// A dummy link, just to make sure that the section appears
-		$template->data['language_urls'][] = [
-			'href' => '#',
-			'text' => '',
-			'class' => 'uls-p-lang-dummy',
-		];
+		// Set to an empty array, just to make sure that the section appears
+		if ( $template->get( 'language_urls' ) === false ) {
+			$template->set( 'language_urls', [] );
+		}
 
 		return true;
 	}