Idea: add "hash=" attribute to HTML anchor tags?

Just had an idea that I wanted to share: Why not add a hash attribute to HTML anchor tags? This would enable secure web sites to also secure links to off-site hosted resources such as scripts from CDNs by specifying their (e.g. SHA-256) cryptographic hash. If the content does not match that hash, an error occurs. It would also make it easy to host large or heavily-trafficked data on fast non-SSL CDN servers and then securely reference it without worrying about it being MITMed, or implement an additional layer of intra-site security even within an SSL-enabled site for defense in depth. Browsers could permit non-SSL data to be linked without a warning provided it was hash-authenticated. Thoughts?