Re: [PATCH v14 0/2] MR3391: mshtml: implement window.MutationObserver with MutationObserver stub

[Gabriel Ivăncescu (＠insn)]

Gabriel Ivăncescu (@insn) commented about dlls/mshtml/mutation.c:
> +{
> - struct mutation_observer_ctor *This = mutation_observer_ctor_from_DispatchEx(dispex);
> - VARIANT *callback;
> - IWineMSHTMLMutationObserver *mutation_observer;
> - HRESULT hres;
> - int argc = params->cArgs - params->cNamedArgs;
> -
> - TRACE("(%p)->(%lx %x %p %p %p %p)\n", This, lcid, flags, params, res, ei, caller);
> -
> - if (argc < 1)
> -
>    return E_UNEXPECTED;
> -
> - if (!res) {
> -
>    /* This function has no side effects if the return value is dropped. */
> -
>    return S_OK;
> - }

Are you sure this should be checked *before* validating `callback`? What happens if you write (in tests):

```jscript
    MutationObserver(42);
```