title: how to set a textbox text dynamically in fabric js Itext
body: <p>i create a canvas, i add a fabric Itext, i want to fill text of textbox in Itext.
  my html code is...</p>
  
  <pre><code> &lt;input type="text" id="title" placeholder="Your Title" /&gt;&lt;br&gt;
  &lt;canvas id="c"&gt;&lt;/canvas&gt;
  </code></pre>
  
  <p>and javascript...</p>
  
  <pre><code>function Addtext() { 
  var text = new fabric.IText('Enter text here...',      {fontSize:16,left:20,top:20,radius:10});
  borderRadius = "25px";
  canvas.add(text).setActiveObject(text);
  text.hasRotatingPoint = true;
  }
  
  document.getElementById('title').addEventListener('keyup', function () {
  var stringTitle = document.getElementById('title').value;
  });
  </code></pre>
  
  <p>please help...thanks in advance.</p>