Note that web-platform-tests has frequent runs of the included browsers in both nightly/dev/tech preview configurations and in stable configurations. And in all

Note that web-platform-tests has frequent runs of the included browsers in both nightly/dev/tech preview configurations and in stable configurations. And in all browsers there can be things which are enabled in these experimental builds which aren't going to ship in the next release. One can argue of course that it makes more sense to make all the comparisons on the basis of what's actually shipped to users, but that wouldn't have changed the story here.