anchor.diff:        throw new Exception(NO_WEBGL_MESSAGE);
       }
   
  +
  +    dynamic actual = _gl.getContextAttributes();
  +/*
  +    LogInfo("alpha: ${actual.alpha}");
  +    LogInfo("antialias: ${actual.antialias}");
  +    LogInfo("depth: ${actual.depth}");
  +    LogInfo("stencil: ${actual.stencil}");
  +    LogInfo("premultipliedAlpha: ${actual.premultipliedAlpha}");
  +    LogInfo("preserveDrawingBuffer: ${actual.preserveDrawingBuffer}");
  +    LogInfo("failIfMajorPerformanceCaveat: ${actual.failIfMajorPerformanceCaveat}");
  +*/
       _gl.clearColor(0.0, 0.0, 0.0, 1.0);
       _gl.enable(GL_DEPTH_TEST);
       if (faceCulling) {
  
positive.code:     _gl.enable(kind);
    }
  
    void disable(int kind) {
      _gl.disable(kind);
    }
  
negative.code:       "antialias": antialiasing,
        "premultipliedAlpha": true,
        "preserveDrawingBuffer": preserveDrawingBuffer,
        "failIfMajorPerformanceCaveat": false,
      };
  
      _gl = _canvas.getContext("webgl2", attributes);
  