title: Javascript stringify '%%' loses a percent sign
body: <p>Why is the output of stringify missing a percent sign?</p>
  
  <pre><code>var a = ["dp",'%%'];
  var t = JSON.stringify (a);
  console.log ('t: ' + t);
  </code></pre>
  
  <p>Result is:</p>
  
  <pre><code>t: ["dp","%"]
  </code></pre>
  
  <p>Why isn't the result:</p>
  
  <pre><code>t: ["dp","%%"]
  </code></pre>
  
  <p>Thanks!</p>