如何在 link 中处理两个 rel= 属性?

How are two rel= attributes treated in a link?

给定一个看起来像这样的 link(我知道这是错误的):

<a href="http://www.something.com/" rel="foo" rel="nofollow">something</a>

根据 html 标准,这必须如何处理,搜索引擎(即 Google)实际上如何处理它?它最终会变成 "foo nofollow"、"foo" 还是 "nofollow"?

我偶然发现了这一点,因为我注意到在 Google Chrome 开发人员工具中,元素显示如下 ...

虽然我测试了一些插件,其中将 link 突出显示为 nofollow

来自spec

When the user agent leaves the attribute name state (and before emitting the tag token, if appropriate), the complete attribute's name must be compared to the other attributes on the same token; if there is already an attribute on the token with the exact same name, then this is a parse error and the new attribute must be removed from the token.

所以第二个将被删除。