Bug 1584471 - Skip test_sanitize_domain.html on fission; r=mccr8

Skip frequently crashing test on fission (it was already marked as failing).

Differential Revision: https://phabricator.services.mozilla.com/D47694

--HG--
extra : moz-landing-system : lando

dom/serviceworkers/test/mochitest.ini

@@ -316,7 +316,7 @@ fail-if = fission
 skip-if = serviceworker_e10s
 [test_sanitize.html]
 [test_sanitize_domain.html]
-fail-if = fission
+skip-if = fission # bug 1584471
 [test_serviceworker.html]
 [test_service_worker_allowed.html]
 [test_serviceworker_header.html]