This tests that we don't include overflow decorations from our ancestor nodes in the drag image for -webkit-user-drag: element. To perform this test drag the green square below. The drag image should not contain any parts of the scrollbar graphics visible on the page.
<div style="height:100px; width:100px;overflow:scroll;">
<div style="-webkit-user-drag:element;position:absolute; background: rgba(0,128,0,0.5); height:100px; width:100px;">
Drag me!
</div>
</div>