In Blender 2.8, we can now drag and split the editors from any corner. For this reason, the corner action zone indicators are no longer necessary because this applies to all corners.
However, the problem is that the scrollbars were moved in to overlap the action zone. This means that it's impossible to use the zoom handles in the corners, because the action zones overlap:
In 2.7x, there was a bit of space for the action zone. We should reinstate that again: