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

Part of MDL-55071

lib/php-css-parser/Parsing/SourceException.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace Sabberworm\CSS\Parsing;
+
+class SourceException extends \Exception {
+	private $iLineNo;
+	public function __construct($sMessage, $iLineNo = 0) {
+		$this->iLineNo = $iLineNo;
+		if (!empty($iLineNo)) {
+			$sMessage .= " [line no: $iLineNo]";
+		}
+		parent::__construct($sMessage);
+	}
+
+	public function getLineNo() {
+		return $this->iLineNo;
+	}
+}