Sorry, using the present tense for things that will be in browsers years later (hopefully) is a common practice that's an issue with me. Let's stick with what people can actually use today.
Also, pointing to features people can use in different dialects of JavaScript is not really fair. Just about everything you can think of has been experimented with and probably deployed somewhere. It doesn't count unless it's all available in the same toolchain and can be used in a unified way while writing a single app.