Interestingly, after setting sideEffects: false, the build now lose polyfills.js.
I think it's time to remove them anyway.

If you want to stop support for IE, I'd like to revive #18091 😇 .

@Mugen87 what I was going to do next is adding the required polyfills in https://threejs.org/examples/misc_legacy.html

@Mugen87 Yes, I think reviving #18091 makes sense. The clean up to CSS3DRenderer definitely. But for the common use case (WebGL) I think it'd be good if we can point people to misc_legacy.html just so they know it's possible to make it work but it's up to them to add the required polyfills.

Okay, sounds fine. I'll make a new PR for CSS3DRenderer only.

Also updated the migration guide to highlight the polyfills change: https://github.com/mrdoob/three.js/wiki/Migration-Guide#r125--r126

@marcofugaro I believe with sideEffects:false we can remove the /*#__PURE__*/ comments? or was that for something else again?

that's a question for @ianpurvis, could you test with shakediff if the /*@__PURE__*/ annotations are still needed? 🙏

@Mugen87 I think after d401181 and b4b24e3, #18091 is done?

Yes, indeed! There are some minor documentation changes left but these can be handled later.