Remove IE11 from the list of supported browsers

[desrosj]

IE11 will no longer be supported by WordPress starting in version 5.8.

The browserslist array needs to be updated to reflect this.

For context, see:

• ​https://make.wordpress.org/core/2021/03/04/discussion-dropping-support-for-ie11/
• ​https://make.wordpress.org/core/2021/03/25/discussion-summary-dropping-support-for-ie11/
• ​https://make.wordpress.org/core/2021/04/22/ie-11-support-phase-out-plan/

[desrosj]

In 50784:

Build/Test Tools: Remove Internet Explorer 11 from the browserslist.

This officially removes support for Internet Explorer 11 in the CSS files run through the build process in Core.

Individual tickets should be opened for removing each manually maintained area of the code base targeting IE11.

The resulting changes to CSS files are included in this commit.

Fixes #53077.

[gziolo]

There is also @wordpress/browserslist-config package that @netweb created. Should we align those two configs and make the npm package a source of truth for consistency?

[netweb]

Using and aligning these would be great :)

I just removed IE 11 for the browser support handbook page (And added a changelog note)

​https://make.wordpress.org/core/handbook/best-practices/browser-support/

[SergeyBiryukov]

Replying to netweb:

I just removed IE 11 for the browser support handbook page (And added a changelog note)

​https://make.wordpress.org/core/handbook/best-practices/browser-support/

Thanks! Expanded the changelog a bit to also mention removing support for IE 6 to 10.

[desrosj]

Replying to gziolo:

There is also @wordpress/browserslist-config package that @netweb created. Should we align those two configs and make the npm package a source of truth for consistency?

Having a source of truth sounds great. But a disadvantage is that the browser list for Core is now buried in a separate repo on GitHub several folders deep. I am not up to date on best practices for maintaining browserslists for projects, but in my opinion, explicitly including it within the package.json file could potentially make for a better contributor experience, mostly because it's easier to find and more apparent.

[audrasjb]

Adding needs-docs keyword to make sure to udpate the requirements in end-user documentation, if necessary.

[audrasjb]

Dev note published: ​https://make.wordpress.org/core/2021/06/28/miscellaneous-developer-focused-changes-in-wordpress-5-8/