Fix extending of class (#1363)

Fix extending of class

Author: lex111

1-js/09-classes/04-private-protected-properties-methods/article.md

@@ -248,7 +248,7 @@ Unlike protected ones, private fields are enforced by the language itself. That'
 But if we inherit from `CoffeeMachine`, then we'll have no direct access to `#waterAmount`. We'll need to rely on `waterAmount` getter/setter:
 
 ```js
-class MegaCoffeeMachine extends CoffeeMachine() {
+class MegaCoffeeMachine extends CoffeeMachine {
   method() {
 *!*
     alert( this.#waterAmount ); // Error: can only access from CoffeeMachine