Source of Recommended/Discouraged algorithms

(I'm not sure if this is appropriate for a github issue but I couldn't find a better place)

In the "Web Cryptography API Live Table" some algorithms are marked as "Recommended" and others are "Discouraged! Only use for backwards compatibility!" What is the source of this classification?

I had a quick look at spec and didn't find it there. Though I did find "suggested" algorithms [here](https://www.w3.org/TR/WebCryptoAPI/#algorithm-recommendations-implementers) and according to the list `AES-CBC` is suggested/recommended, while according to the project's table it's `AES-GCM` which is recommended and all other cypher modes are "discouraged".