Re: Making selectors first-class citizens

For the record, I'm equally concerned about renaming `matchesSelector` into `matches`.

A lot of code now rely on a prefixed or unprefixed version of `matchesSelector` as this has shipped in an interoperable fashion in all browsers now.

I don't mind adding a new `matches` function that would take a Selector as an argument, or simply consider matchesSelector as a deprecated API and recommend to use Selector going forward, with a polyfill for older browsers, but I believe renaming `matchesSelector` at this time is a dangerous idea. The other option to keeping `matchesSelector` as is is to continue to ship the prefixed versions forever which seems a bad idea to me.

-- standardize what's implemented, implement what's standardized.