title: React onDrop is not firing
body: <p>Below is the sample code which I'm trying to use, which is react + TypeScript.
  onDragEnter and onDragOver are working properly but not the <strong>onDrop</strong> event.</p>
  <pre><code>import * as React from 'react';
  
  export class FileZone extends React.Component {
  
    onDragOver = (e) =&gt; {
      let event = e as Event;
      event.stopPropagation();
    }
  
    onDragEnter = (e) =&gt; {
      let event = e as Event;
      event.stopPropagation();
    }
  
    onFileDrop = (e) =&gt; {
      let event = e as Event;
      event.stopPropagation();
  
      console.log(&quot;onFileDrop&quot;);
      alert(&quot;dropped&quot;)
    }
  
    render() {
      return (
        &lt;div
          onDragEnter={this.onDragEnter}
          onDragOver={this.onDragOver}
          onDrop={this.onFileDrop}&gt;
          Drag and drop file here
        &lt;/div&gt;)
    }
  }
  </code></pre>