testRemoveDragItemHoverClasses() {
    dlg.handleDragItemMouseover_(event);
    dlg.handleDragItemMouseout_(event);

    assertFalse(
        'Should have no cursor_move class after MOUSEOUT',
        classlist.contains(event.currentTarget, 'cursor_move'));
    assertFalse(
        'Should have no cursor_pointer class after MOUSEOUT',
        classlist.contains(event.currentTarget, 'cursor_pointer'));
    assertFalse(
        'Should have no opacity_40 class after MOUSEOUT',
        classlist.contains(event.currentTarget, 'opacity_40'));
    assertFalse(
        'Should have no blue_bg class after MOUSEOUT',
        classlist.contains(event.currentTarget, 'blue_bg'));
  }
Test the effect of stopping hovering over a list.
Check that after the MOUSEOUT browser event all CSS classes are removed
from the target (as we are no longer hovering over the it).
@suppress {visibility,checkTypes} suppression added to enable type checking