message: invoke constructor on existing Bezier object instance
diff: ensureBezierLib();
  scratch = new Bezier(bezierJsPoints);
  } else {
  - scratch.points = bezierJsPoints;
  - scratch.update();
  + //invoke the constructor on the same object
  + Bezier.apply(scratch, bezierJsPoints);
  }
  return scratch;
  