[wp-trac] [WordPress Trac] #56699: Remove IE specific checks from default themes

[WordPress Trac]

#56699: Remove IE specific checks from default themes
---------------------------+-----------------------------
 Reporter:  desrosj        |      Owner:  (none)
     Type:  enhancement    |     Status:  new
 Priority:  normal         |  Milestone:  Awaiting Review
Component:  Bundled Theme  |    Version:
 Severity:  normal         |   Keywords:
  Focuses:                 |
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 In several default themes, there are a number of different things
 targeting old browsers:
 - stylesheets targeting specific versions of IE
 - an [https://github.com/aFarkas/html5shiv HTML5 shiv] targeting IE 6-9,
 Safari 4.x, and Firefox 3.x.

 [https://make.wordpress.org/core/2017/04/23/target-browser-coverage/
 Support for IE < 11 was dropped in WordPress 4.8] (2017). Safari 4.x and
 Firefox 3.x has not been supported for quite a bit longer (the auto-
 prefixing in Grunt.js was introduced almost 10 years ago in [27078] with
 support for `Firefox >= 17` and `Safari >= 6.0`).

 While it can be argued that themes were designed to support a specific set
 of browsers and that should not change as time goes on, the following data
 about browser usage should make it clear why this continuing to include
 these files is unnecessary:

 - All [https://browserslist.dev/?q=ZGVhZA%3D%3D versions of IE have been
 considered "dead"] (no official support or updates for at least 24 months)
 for some time now.
 - [https://browserslist.dev/?q=RmlyZWZveCA8IDQgYW5kIEZpcmVmb3ggPiAy
 Firefox 3.x has 0.014% market share].
 - [https://browserslist.dev/?q=U2FmYXJpIDQ%3D Safari 4.x has 0.000% market
 share].

 Themes affected:
 - Twenty Eleven
 - Twenty Twelve
 - Twenty Thirteen
 - Twenty Fourteen
 - Twenty Fifteen
 - Twenty Sixteen
 - Twenty Seventeen

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Ticket URL: <https://core.trac.wordpress.org/ticket/56699>
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