title: How to set defaultProps for function?
body: <p>Is it possible to set defaultProps for functions? Code below doesn't work. It doesn't like 'this'. I tried 1_ bind defaultProps to 'this', or 2_ bind handleClose to 'this', neither works. I use ES6 class.</p>
  
  <pre><code>SaveDialog.propTypes = {
    note: React.PropTypes.string,
    onCancel: React.PropTypes.func,
    onSave: React.PropTypes.func,
    onEditChange: React.PropTypes.func
  };
  
  SaveDialog.defaultProps = {
    note: '',
    onCancel: {this.handleClose},
    onSave: {this.handleClose},
    onEditChange: {this.handleChange}
  };
  </code></pre>