title: Drag & Drop functionality lost when fabric.Canvas is initialized
body: <p>I have this canvas in the HTML and the D&amp;D works fine:</p>
  
  <pre><code>&lt;canvas id="canvas" width="800" height="450" ondragover="onDragOver($event)" ondrop="onDrop($event)"&gt;&lt;/canvas&gt;
  </code></pre>
  
  <p>but when I want to create an instance of fabric.js to make use of the API, the D&amp;D functionality is lost.</p>
  
  <pre><code>this.canvasObj = new fabric.Canvas('canvas', {});
  </code></pre>
  
  <p>How can I preserve the functionality?</p>