Transform of dragged elements causes overlap of adjacent content

[ohepworthbell]

Problem

When a sortable element is dragged, an attribute of transform: translateZ(0) is added (looks like to fix an old rendering issue in Chrome - #1276); however, when the element is dropped this attribute is not removed, resulting in any absolutely position children of the draggable element (such as a tooltip) that extend past their parent's bounds to be overlapped by any following dragged/draggable elements.

To recreate

https://jsfiddle.net/4kcbzLse/

1. Add 2-3 list items using button
2. Drag a list item to the top
3. Hover over tooltip on the right of dragged list item
4. Observe how border of following item overlaps

Fix is very easy - just need to add a line:

css(dragEl, 'transform', '')

To line 1353 of ./src/Sortable.js (within the _onDrop: function() { ... } call). This will remove the attribute again once an element has been dropped.

Tested locally and fixes the issue for me, though to be clear - I have not experienced the issue #1276 myself, so not sure if this will cause conflicts with that. Might be worth further testing

[ohepworthbell]

Should add: happy to do a PR, though given further testing is required might be best if someone who is familiar with original issue has a look?

[owen-m1]

Merged PR in e979370