Fetch API: Fix behavior when Request constructor is passed an undefined referrer

third_party/WebKit/LayoutTests/external/wpt/service-workers/service-worker/fetch-event.https-expected.txt

Index: third_party/WebKit/LayoutTests/external/wpt/service-workers/service-worker/fetch-event.https-expected.txt
diff --git a/third_party/WebKit/LayoutTests/external/wpt/service-workers/service-worker/fetch-event.https-expected.txt b/third_party/WebKit/LayoutTests/external/wpt/service-workers/service-worker/fetch-event.https-expected.txt
index 9790584edac241fc99155e48ce774940710dec8c..2475a94ee3028ea5eef6751288fd48aac3f87add 100644
--- a/third_party/WebKit/LayoutTests/external/wpt/service-workers/service-worker/fetch-event.https-expected.txt
+++ b/third_party/WebKit/LayoutTests/external/wpt/service-workers/service-worker/fetch-event.https-expected.txt
@@ -2,7 +2,7 @@ This is a testharness.js-based test.
 PASS Service Worker responds to fetch event with string 
 PASS Service Worker responds to fetch event with blob body 
 PASS Service Worker responds to fetch event with the referrer URL 
-FAIL Service Worker responds to fetch event with the referrer policy assert_unreached: unexpected rejection: assert_equals: Service Worker should respond to fetch with the referrer URL when a member of RequestInit is present expected "Referrer: https://web-platform.test:8444/service-workers/service-worker/resources/simple.html?referrerPolicy\nReferrerPolicy: no-referrer-when-downgrade" but got "Referrer: https://web-platform.test:8444/service-workers/service-worker/resources/undefined\nReferrerPolicy: no-referrer-when-downgrade" Reached unreachable code
+FAIL Service Worker responds to fetch event with the referrer policy assert_unreached: unexpected rejection: Failed to fetch Reached unreachable code
 PASS Service Worker responds to fetch event with an existing client id 
 PASS Service Worker does not respond to fetch event 
 PASS Service Worker responds to fetch event with null response body