HTMLObjectElement：willValidate 属性
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since 2015年7月.
HTMLObjectElement 接口的 willValidate 只读属性返回一个指示元素是否为约束验证的候选者的布尔值。对于 HTMLObjectElement 对象，始终为 false。