function isCursorOverDragger(dlg, newMousePosition) {
  const draggedElRect = dlg.draggerEl_.getBoundingClientRect();
  const isContainedInWidth = draggedElRect.left <= newMousePosition.x &&
      draggedElRect.right >= newMousePosition.x;
  const isContainedInHeight = draggedElRect.top <= newMousePosition.y &&
      draggedElRect.bottom >= newMousePosition.y;

  return isContainedInWidth && isContainedInHeight;
}
Whether the mouse is over the currently dragged element.
@param {!DragListGroup|null} dlg The DragListGroup to examine
@param {!Coordinate} newMousePosition The mouse cursor position
@return {boolean} Whether the cursor is over the draggerEl or not
@suppress {visibility} suppression added to enable type checking