Remove unnecessary constructor method

client/source/scripts/components/torrent-list/ProgressBar.js

@@ -1,11 +1,6 @@
 import React from 'react';
 
 export default class ProgressBar extends React.Component {
-
-  constructor() {
-    super();
-  }
-
   render() {
     let percent = this.props.percent;
     let className = 'progress-bar';
@@ -16,5 +11,4 @@ export default class ProgressBar extends React.Component {
       </div>
     );
   }
-
 }