Constructor for ssURLLoader. Creates a new instance of ssURLLoader.
First available in version 3.5 build 314.
Available only in ActionScript 3.
request - URLRequest - [Optional] - Optional URLRequest object that specifies the path to the file to load. Default value is null.
Constructor; The path specified for the url property of the request object passed is a path relative to the root of the layout (see the Files Tab). Only files within the layout can be loaded. If you leave the URLRequest object out you will need to call the load() method to load a file.