tell my what you think here, but I'd do something like:
* make `scrollViewToBottom` return "true" if it could scroll, and "false" if it couldn't
* add this code here:
```javascript
if (!ThreadUI.scrollViewToBottom()) {
  ThreadUI.showNewMessageBanner();
}
```

or (same code, more compact but maybe less readable, choose what you want):
```javascript
ThreadUI.scrollViewToBottom() || ThreadUI.showNewMessageBanner();
```
and you can remove any conditional from `showNewMesasgeBanner`.

I think it makes the code very easy to read, because the functions do what their name implies.