Update class.md

docs/class.md

@@ -599,7 +599,7 @@ obj.toString(); // MyObject: [object Object]
 var p1 = new Point(2, 3);
 var p2 = new ColorPoint(2, 3, 'red');
 
-p2.__proto__ === p1.__proto // false
+p2.__proto__ === p1.__proto__ // false
 p2.__proto__.__proto__ === p1.__proto__ // true
 ```