function getComputedStyle(element) {
  var rootWindow = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : window;
  return element.currentStyle || rootWindow.getComputedStyle(element);
}
Returns a computed style object for the provided element. (Needed if style is declared in external stylesheet).

@param element
@param {Window} rootWindow
@returns {IEElementStyle|CssStyle} Elements computed style object