Bug 1808229 - Enable :nth-child(... of <selector>) in all release channels r=emilio

Differential Revision: https://phabricator.services.mozilla.com/D172838

modules/libpref/init/StaticPrefList.yaml

@@ -8581,7 +8581,7 @@
 # Before enabling everywhere, make sure blockers of bug 1808229 are fixed.
 - name: layout.css.nth-child-of.enabled
   type: RelaxedAtomicBool
-  value: @IS_NIGHTLY_BUILD@
+  value: true
   mirror: always
   rust: true
 

testing/web-platform/meta/css/css-conditional/js/CSS-supports-L4.html.ini

@@ -1,4 +0,0 @@
-[CSS-supports-L4.html]
-  prefs: [layout.css.nth-child-of.enabled:true]
-  expected:
-    if (os == "android") and fission: [OK, TIMEOUT]

testing/web-platform/meta/css/selectors/__dir__.ini

@@ -1,3 +1,3 @@
 lsan-disabled: true
-prefs: [gfx.font_rendering.fallback.async:false, layout.css.has-selector.enabled:true, layout.css.nth-child-of.enabled:true, dom.focus.fixup:true]
+prefs: [gfx.font_rendering.fallback.async:false, layout.css.has-selector.enabled:true, dom.focus.fixup:true]
 leak-threshold: [default:3276800, tab:460800]