example code must be unexecutable

example code must be executable because, it has dependent on another example code above. So it can't work in plunker container.

Author: lumosmind

1-js/09-classes/02-class-inheritance/article.md

@@ -40,7 +40,7 @@ The syntax to extend another class is: `class Child extends Parent`.
 
 Let's create `class Rabbit` that inherits from `Animal`:
 
-```js run
+```js
 *!*
 class Rabbit extends Animal {
 */!*