anchor.diff:  // limitations under the License.
   
   part of cocos;
  +
  +const DEBUG = false;
   
   class Game {
     AssetManager assets;
  
positive.code:     new Timer.periodic(new Duration(seconds:1), (t) {
        fps = frameCount;
        frameCount = 0;
        print('fps: $fps');
      });
    }
  }
  
negative.code: 
    void draw(CanvasRenderingContext2D context) {
      context.clearRect(0, 0, canvas.width, canvas.height);
      if (DEBUG) _debugDraw(context);
      currentScene.drawWithChildren(context);
    }
  
    void run([Scene scene]) {
      if (scene == null) {
        scene = new Scene();
      }
      currentScene = scene;
      
      var initTime;
      var frameCount = 0;
  
      drawFrame(num currentTime) {
        if (initTime == null) {
  