Customize: remove support for IE8
|Reported by:||celloexpressions||Owned by:||ryankienstra|
It is difficult to maintain support for Internet Explorer 8, and we typically no longer notice issues until close to or even after a release. The customizer already doesn't support IE7, or IE8 or 9 with domain mapping, so we can build on the no-customize-support class to actually make the customizer inaccessible on IE8.
The relevant code is in wp_customize_support() in wp-includes/theme.php. It uses feature detection in JS; we should add a check for something that isn't supported by IE8 but is supported by IE9 and other browsers. Ideally it should be something we've broken in IE8 in the customizer before.