Bug 1941406: Enable support for the ::details-content pseudo-element. r=emilio

Differential Revision: https://phabricator.services.mozilla.com/D257081

Author: dholbert

layout/reftests/details-summary/details-percentage-height-children.html

@@ -9,6 +9,10 @@
     width: 500px;
     height: 300px;
   }
+  ::details-content {
+    /* Ensure content doesn't prevent div spanning height */
+    display: contents;
+  }
   summary {
     /* Hide the triangle for comparing with div in reftest. */
     list-style-type: none;

modules/libpref/init/StaticPrefList.yaml

@@ -10715,7 +10715,7 @@
 # Is support for the ::details-content pseudo-element enabled?
 - name: layout.css.details-content.enabled
   type: RelaxedAtomicBool
-  value: false
+  value: true
   mirror: always
   rust: true
 

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

@@ -1,2 +1,2 @@
-prefs: [layout.css.details-content.enabled:true, layout.css.scroll-state.enabled:true]
+prefs: [layout.css.scroll-state.enabled:true]
 leak-threshold: [default:51200]

testing/web-platform/meta/css/css-conditional/js/__dir__.ini

@@ -1,2 +1 @@
-prefs: [layout.css.details-content.enabled:true]
 leak-threshold: [default:51200]

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

@@ -1 +1 @@
-prefs: [layout.css.details-content.enabled:true, dom.viewTransitions.enabled:true]
+prefs: [dom.viewTransitions.enabled:true]

testing/web-platform/meta/css/css-shadow-parts/__dir__.ini

@@ -1,2 +1 @@
-prefs: [layout.css.details-content.enabled:true]
 leak-threshold: [default:51200]