function getScrollAncestorsOverflowY(node, acc = new Map()) {
  const scrollingRoot = getScrollingRoot();
  const scrollParent = getScrollParent(node);
  acc.set(scrollParent, scrollParent.style.overflowY);

  if (scrollParent === scrollingRoot) return acc;
  return getScrollAncestorsOverflowY(scrollParent, acc);
}
Recursively traverses the tree upwards from the given node, capturing all
ancestor nodes that scroll along with their current 'overflow-y' CSS
property.

@param {HTMLElement} node Any DOM element.
@param {Map<HTMLElement,string>} [acc] Accumulator map.
@return {Map<HTMLElement,string>} Map of ancestors with their 'overflow-y' value.