Fix rSAFor WPT dual-write test case

The purpose of this test is to verify that a successful
requestStorageAccessFor() call also sets a storage-access grant so
that requestStorageAccess() should be resolved without a user gesture.
However the test was testing this behavior in a same-origin iframe,
in which case requestStorageAccess() is resolved not due to the
existing grant.

Change-Id: Ic16702271d1bed1f4faaacdd3ebef0dc152fecb5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4721492
Reviewed-by: Chris Fredrickson <cfredric@chromium.org>
Commit-Queue: Chris Fredrickson <cfredric@chromium.org>
Auto-Submit: Shuran Huang <shuuran@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1175699}

top-level-storage-access-api/tentative/requestStorageAccessFor.sub.https.window.js

@@ -78,7 +78,7 @@ promise_test(
           'granted');
 
       const frame = await CreateFrame(
-        '/storage-access-api/resources/script-with-cookie-header.py?script=embedded_responder.js');
+        altOrigin + '/storage-access-api/resources/script-with-cookie-header.py?script=embedded_responder.js');
 
       await RunCallbackWithGesture(() => document.requestStorageAccessFor(altOrigin));
       assert_true(await RequestStorageAccessInFrame(frame));