Bug 1648508 - Update assert count for service-worker tests,

Differential Revision: https://phabricator.services.mozilla.com/D81856

testing/web-platform/meta/service-workers/service-worker/fetch-event-redirect.https.html.ini

@@ -0,0 +1,2 @@
+[fetch-event-redirect.https.html]
+  max-asserts: 2

testing/web-platform/meta/service-workers/service-worker/update-bytecheck.https.html.ini

@@ -0,0 +1,2 @@
+[update-bytecheck.https.html]
+  max-asserts: 2