function getUnboundedScrollPosition(scrollable) {
	  if (scrollable === window) {
	    return {
	      x: window.pageXOffset || document.documentElement.scrollLeft,
	      y: window.pageYOffset || document.documentElement.scrollTop
	    };
	  }
	  return {
	    x: scrollable.scrollLeft,
	    y: scrollable.scrollTop
	  };
	}
Gets the scroll position of the supplied element or window.

The return values are unbounded, unlike `getScrollPosition`. This means they
may be negative or exceed the element boundaries (which is possible using
inertial scrolling).

@param {DOMWindow|DOMElement} scrollable
@return {object} Map with `x` and `y` keys.