anchor.diff:      new Timer(const Duration(milliseconds: 16), () {
         _callRAF(fn);
       });
  +    return 1;
     }
   
     void cancelAnimationFrame(int id) {
  
positive.code: }
  
  class HTMLImageElement extends Element {
    Image();
    String src;
    Object style = {};
  }
  
negative.code: Window window = new Window();
  
  class ClientRect {
      double top;
      double right;
      double bottomr;
      double left;
  