MDL-55224 core: Import PHP-CSS-Parser into core

Part of MDL-55071

lib/php-css-parser/Comment/Commentable.php

@@ -0,0 +1,23 @@
+<?php
+
+namespace Sabberworm\CSS\Comment;
+
+interface Commentable {
+
+	/**
+	 * @param array $aComments Array of comments.
+	 */
+	public function addComments(array $aComments);
+
+	/**
+	 * @return array
+	 */
+	public function getComments();
+
+	/**
+	 * @param array $aComments Array containing Comment objects.
+	 */
+	public function setComments(array $aComments);
+
+
+}