H5 Safari issue dragging from outside over existing grid item #1550

Subject of the issue

while fixing #1540 and using two.html, I discovered that you cannot drag an item into a grid IFF you already have an item there on Safari mac only (fine on Chrome Mac or Chrome/FF/Edge windows). It should push the items down... guessing we're not getting dropover event on Safari for some reason...

Makes me wonder if HTML5 drag&drop is really worth the browser compat issues (only safari so far) as we already fight draggable to not show gost images and other issues... vs simple mouse handling (like resizing).

Your environment

• 3.1.2 dev fixes
• safari mac - fine on Chrome and all Windows browsers (Chrome/FF/Edge)