Optimization for extended classes in ADVANCED_OPTIMIZATIONS

Hello. I have the following javascript code:

```
class Base{
something(){
console.log("base");
}
}

class CoolBase extends Base{
something(){
console.log("cool");
}
}
var a=new CoolBase();
a.something();
```

I'm trying to compile this in ADVANCED_OPTIMIZATIONS .
if I use a simple(not extended) class for example

```
var a=new Base();
a.something();
```

the output is nice and clean: `console.log("base");`

If I use the extended class

```
var a=new CoolBase();
a.something();
```

I get something like this:
`function d(a,b){function e(){}e.prototype=b.prototype;a.prototype=new e;a.prototype.constructor=a;for(var c in b)if(Object.defineProperties){var f=Object.getOwnPropertyDescriptor(b,c);f&&Object.defineProperty(a,c,f)}else a[c]=b[c]}function g(){}g.prototype.a=function(){console.log("base")};function h(){}d(h,g);h.prototype.a=function(){console.log("cool")};(new h).a();`

instead of `console.log("cool");`

It would be nice to optimize this. not sure if it's possible or by fixing this, can lead to other errors.

Thanks