Added window.requestAnimationFrame.

samples/openglui/src/openglui_raytrace.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 //
 // This sample is based upon the Ray Tracer sample by Jonas Sicking at:
 // http://www.khronos.org/webgl/wiki/Demo_Repository
 
 /**
  * A sample GL application.
  */
@@ skipping 327 matching lines @@
 void setup(canvas, int w, int h) {
   if (canvas == null) {
     canvas = new CanvasElement(width: w, height: h);
   }
   gl = canvas.getContext("experimental-webgl");
   initShaders();
   gl.clearColor(0.0, 0.0, 0.0, 1.0);
   gl.clearDepth(1.0);
   initBuffers();
   resize(w, h);
+  requestAnimationFrame(update);
   log("Done setup");
 }
 
 void resize(int width, int height) {
   gl.viewport(0, 0, width, height);
   ratio = width / height;
   t -= 0.03;
   drawScene();
 }
 
-void update() {
+void update(when) {
   drawScene();
+  requestAnimationFrame(update);
 }
 
 onMotionDown(num when, num x, num y) {
 }