Safari Tech Preview 238 supports :open (#29180)

Author: lukewarlow

css/selectors/open.json

@@ -34,7 +34,7 @@
             "opera": "mirror",
             "opera_android": "mirror",
             "safari": {
-              "version_added": false
+              "version_added": "preview"
             },
             "safari_ios": "mirror",
             "samsunginternet_android": "mirror",