title: adding stroke to google chart
body: <p>I have created an google area chart and give a pointSize of 5 as my screenshot below.<img src="https://i.stack.imgur.com/0eo1J.png" alt="enter image description here"></p>
  
  <p>Is there a way to add a stroke to my points like the image below.
  <img src="https://i.stack.imgur.com/QI9j2.png" alt="enter image description here"></p>