scrollTo和scrollBy兩個api的兼容

/**
 * @description scrollTo/scrollBy的polyfill
 *              IE9+
 * @author zhangxinxu(.com)
 * @created 2019-07-27
 */

if (!window.scrollTo) {
	window.scrollTo = function (x, y) {
		window.pageXOffset = x;
		window.pageYOffset = y;
	};
}
if (!window.scrollBy) {
	window.scrollBy = function (x, y) {
		window.pageXOffset += x;
		window.pageYOffset += y;
	};
}
if (!document.body.scrollTo) {
	Element.prototype.scrollTo = function (x, y) {
		this.scrollLeft = x;
		this.scrollTop = y;
	};
}
if (!document.body.scrollBy) {
	Element.prototype.scrollBy = function (x, y) {
		this.scrollLeft += x;
		this.scrollTop += y;
	};
}