Fix notice and wrong Regex (#781)

* Fix

* Update cdn.cls.php

* Changed the rule

* remove extra condition

src/cdn.cls.php

@@ -306,7 +306,7 @@ private function _replace_inline_css()
 		 * @see  #685485
 		 * @since 3.0
 		 */
-		preg_match_all('/url\((?![\'"]?data)[\'"]?([^\)\'"\\\]+)[\'"]?\)/i', $this->content, $matches);
+		preg_match_all('/url\((?![\'"]?data)[\'"]?(.+?)[\'"]?\)/i', $this->content, $matches);
 		foreach ($matches[1] as $k => $url) {
 			$url = str_replace(array(' ', '\t', '\n', '\r', '\0', '\x0B', '"', "'", '"', '''), '', $url);