Safari’s had that for more than two years. (Chromium, more than three, Firefox, almost one.)
> Import Assertions
An excellent example of why Firefox and Safari tend to be more reserved in what they ship, in contrast to Chromium which is much more fond of shipping immature stuff.
Import assertions are dead, superseded by import attributes. V8 has deprecated import assertions and will remove them soon. See https://v8.dev/features/import-assertions for more info on why.
Chromium shipping immature stuff is, from time to time, a real pain, because it makes it harder to fix problems in the spec as you sometimes have to avoid breaking real usage. Sometimes this basically makes things worse forever, because of naming things. I can’t remember a specific case in browsers, but know they exist; but a similar case is how we have some methods named includes instead of contains like they should have been because of Mootools touching stuff it shouldn’t have, and so now everyone suffers for that mistake.