Remove Internet Explorer 11 Support

[markusguenther]

Description

The IE 11 is dead and even some of the libraries we use (ckeditor 5) are not compatible anymore.
So we should remove the IE support and get rid of some polyfills and so one.

As it is to short before the 6.0 release we should tackle that for the next 6.1 version :)

• Remove ckeditor version 4
• Check if we still need polifills
• Cleanup styles and remove potential IE hacks

[markusguenther]

It has been a while ;)
Actually, we are shipping CKEditor 4 and 5. The version 4 is for compatibility reasons because this one worked in the older IE browsers. With version 8.0 I plan to drop this CKEditor version 4.

[mhsdesign]

are the './polyfills.js' still needed? https://github.com/neos/neos-ui/blob/master/polyfills.js

[albe]

Anything left to do on this?

[mhsdesign]

with #3200 we are now targeting es2020, removed (some if not all) polyfills and im working via #3266 on removing the autoprefixer.

i think thats the last task - but hard to get started

Cleanup styles and remove potential IE hacks

maybe it will up itself eventually over time ...

[mhsdesign]

I could find no comments referencing internet explorer, ie, microsoft, or ms (vendor prefixes and stuff)
so i think we can close this ;)