Correct reason not visible when element is detached from DOM

Currently, if an element gets detached/removed from the DOM during actionability, you get:
```
'This element '...' is not visible because it has an effective width and height of: '0 x 0' pixels' 
```

This happens when element is removed or re-rendered on scroll, for example.

We should provide a more precise error message so that this issue can be better resolved: #695 