Added support for passing a canvas id to the Stage constructor.

Signed-off-by: Grant Skinner <info@gskinner.com>

examples/icons.html

@@ -21,21 +21,20 @@
 <!-- End EaselJS Imports -->
 
 <script>
-var canvas;
 var stage;
 
 var iconSheet = new Image();
 
 function init() {
 	//find canvas and load images, wait for last image to load
-	canvas = document.getElementById("testCanvas");
 	iconSheet.onload = handleImageLoad;
 	iconSheet.src = "img/icons.png";
 }
 
 function handleImageLoad() {
 	// create a new stage and point it at our canvas:
-	stage = new Stage(canvas);
+	// note that we can just pass the id of the canvas:
+	stage = new Stage("testCanvas");
 
 	/*** FIRST: the "simple" approach ***/
 	// create a simple SpriteSheet using iconSheet with a frame size of 80x80:

src/easeljs/display/Stage.js

@@ -192,12 +192,12 @@ var p = Stage.prototype = new Container();
 	/**
 	 * Initialization method.
 	 * @method initialize
-	 * param {HTMLCanvasElement} canvas
+	 * param {HTMLCanvasElement} canvas A canvas object, or the string id of a canvas object in the current document.
 	 * @protected
 	 **/
 	p.initialize = function(canvas) {
 		this.Container_initialize();
-		this.canvas = canvas;
+		this.canvas = (canvas instanceof HTMLCanvasElement) ? canvas : document.getElementById(canvas);
 		this._enableMouseEvents(true);
 	}