code: function setStyle(element, styleProps, savedStyleProps, propNames) {
    var style = element.style;
    (propNames || Object.keys(styleProps)).forEach(function (prop) {
      if (styleProps[prop] != null) {
        if (savedStyleProps && savedStyleProps[prop] == null) {
          savedStyleProps[prop] = style[prop];
        }
        style[prop] = styleProps[prop];
        styleProps[prop] = null;
      }
    });
    return element;
  }
docs: Set style properties while saving current properties.
  @param {Element} element - Target element.
  @param {Object} styleProps - New style properties.
  @param {(Object|null)} savedStyleProps - Current style properties holder.
  @param {Array} [propNames] - Names of target properties.
  @returns {Element} Target element itself.