Mentions select are not scrolled when using arrow down key

[OhadTutay]

Steps to reproduce:

1. Use @ to call the suggestion list
2. Place the mouse cursor on one of the list items
3. Use click on the arrow down button.
4. If you continue to click on the arrow down to move further down we keep going back to the item that we placed the cursor on.

Expected behaviour:
We should keep going down and not jump back to the item that we placed the mouse cursor on.

Observed behaviour:
Continue clicking on the arrow down, we keep going back to the item that we placed the cursor on.

Workaround:
There is no workaround

I'm using 4.4.6. since the latest version has another bug (scrolling to the position of the focused item is not working)

[Ranaxl693]

Getting the same issue as I am using V4.4.7.