Mark Safari ::details-content support as partial (#27674)

Mark Safari ::details-content support as partial

Author: lukewarlow

css/selectors/details-content.json

@@ -23,7 +23,10 @@
             "opera": "mirror",
             "opera_android": "mirror",
             "safari": {
-              "version_added": "18.4"
+              "version_added": "18.4",
+              "impl_url": "https://webkit.org/b/283446",
+              "partial_implementation": true,
+              "notes": "Does not support chaining pseudo-elements after `::details-content`."
             },
             "safari_ios": "mirror",
             "samsunginternet_android": "mirror",