Step 11.5: Add a new prop type for Task component.

Task.jsx

@@ -2,9 +2,9 @@
 
 Task = React.createClass({
   propTypes: {
-    // This component gets the task to display through a React prop.
     // We can use propTypes to indicate it is required.
-    task: React.PropTypes.object.isRequired
+    task: React.PropTypes.object.isRequired,
+    showPrivateButton: React.PropTypes.bool.isRequired
   },
 
   toggleChecked() {