[csswg-drafts] [css-shadow-parts] confirm browser support

fergald has just created a new issue for https://github.com/w3c/csswg-drafts:

== [css-shadow-parts] confirm browser support ==
I am planning to implement the ::part() half of the [shadow parts spec](https://drafts.csswg.org/css-shadow-parts/) in Blink. In order to send an Intert To Implement for this (as an experimental feature), I need to know what support there is from other browsers. My understanding is that is that there is broad support for the basics of ::part from supported by Edge, Safari and Firefox. It would be very helpful if you could confirm this here. Thanks.

@travisleithead @smaug @rniwa

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/2368 using your GitHub account