Linter error fixes

src/core/components/try-it-out-button.jsx

@@ -4,11 +4,13 @@ export default class TryItOutButton extends React.Component {
 
   static propTypes = {
     onTryoutClick: PropTypes.func,
+    onCancelClick: PropTypes.func,
     enabled: PropTypes.bool, // Try it out is enabled, ie: the user has access to the form
   };
 
   static defaultProps = {
     onTryoutClick: Function.prototype,
+    onCancelClick: Function.prototype,
     enabled: false,
   };