Allow the specification of a asset base URL.

laravel/url.php

@@ -220,16 +220,14 @@ class URL {
 	 */
 	public static function to_asset($url, $https = null)
 	{
-
-		// If the URL is already well-formed, just return it
 		if (static::valid($url)) return $url;
 
-		// If a base asset URL is defined in the configuration, use that and
-		// don't try and change links to http/https.
-		if ($root = Config::get('application.asset_url', false )) {
-
+		// If a base asset URL is defined in the configuration, use that and don't
+		// try and change the HTTP protocol. This allows the delivery of assets
+		// through a different server or third-party content delivery network.
+		if ($root = Config::get('application.asset_url', false))
+		{
 			return rtrim($root, '/').'/'.ltrim($url, '/');
-
 		}
 
 		if (is_null($https)) $https = Request::secure();