function Scene (selector, updater) {
    if (!selector) throw new Error('Scene needs to be created with a DOM selector');
    if (!updater) throw new Error('Scene needs to be created with a class like Famous');

    Node.call(this);         // Scene inherits from node

    this._globalUpdater = updater; // The updater that will both
                                   // send messages to the renderers
                                   // and update dirty nodes

    this._selector = selector; // reference to the DOM selector
                               // that represents the element
                               // in the dom that this context
                               // inhabits

    this.mount(selector); // Mount the context to itself
                          // (it is its own parent)

    this._globalUpdater                  // message a request for the dom
        .message(Commands.NEED_SIZE_FOR)  // size of the context so that
        .message(selector);               // the scene graph has a total size

    this.show(); // the context begins shown (it's already present in the dom)
}
Scene is the bottom of the scene graph. It is its own
parent and provides the global updater to the scene graph.

@class Scene
@constructor
@extends Node

@param {String} selector a string which is a dom selector
                signifying which dom element the context
                should be set upon
@param {Famous} updater a class which conforms to Famous' interface
                it needs to be able to send methods to
                the renderers and update nodes in the scene graph