WHATWG standards are generally formed by starting from what the 4 major browsers (Chrome, Firefox, IE (Edge), Safari) do. Anything that is done in common by all of them gets implemented no problem. It's when they all differ that the editor(s) tries to come up with more reasoned algorithms.
> WHATWG standards are generally formed by starting from what the 4 major browsers (Chrome, Firefox, IE (Edge), Safari) do.
I thought WHATWG standards are formed by starting with what the four major browser vendors agree to do, not what they currently do (though usually at least one has an implementation before something gets proposed for standardization.)