Test for WebKit bug 15106: Dragging text inside an element with "user

Test for WebKit bug 15106: Dragging text inside an element with "user-drag: element" and "user-select: none" should initiate a drag

This element should be draggable, but initiating a drag from within the text should begin a selection.

This element should not be draggable, and initiating a drag from within the text should not begin a selection.

This element should be draggable, and initiating a drag from within the text should drag the element.