Bug 1729136 - set a step in initial-content-replacement.html as intermittent. DONTBUILD

Test got added in bug 12721813 on Sep 03.

Differential Revision: https://phabricator.services.mozilla.com/D124617

testing/web-platform/meta/html/browsers/browsing-the-web/navigating-across-documents/initial-empty-document/initial-content-replacement.html.ini

@@ -29,7 +29,9 @@
       FAIL
 
   [Content synchronously added to window.open('about:blank')-ed document won't get replaced]
-    expected: FAIL
+    expected:
+      if not swgl and debug and (os == "linux") and not fission: [FAIL, PASS]
+      FAIL
 
   [Content synchronously added to window.open('about:blank?foo')-ed document won't get replaced]
     expected: FAIL