Bug 1762462 - Make tests in layout/base/tests/ reflect Always Partitioning Storage; r=smaug

Depends on D148058

Differential Revision: https://phabricator.services.mozilla.com/D148059

layout/base/tests/test_bug607529.html

@@ -99,9 +99,13 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=607529
     // the iframe containing this page is isolated from first-party storage access,
     // which isolates BroadcastChannel communication.
     SpecialPowers.wrap(document).notifyUserGestureActivation();
-    SpecialPowers.addPermission("storageAccessAPI", true, window.location.href).then(() =>{
-      SpecialPowers.wrap(document).requestStorageAccess().then(() => {
-        executeTest();
+    SpecialPowers.pushPrefEnv({
+      set: [["privacy.partition.always_partition_third_party_non_cookie_storage", false]],
+    }).then(() => {
+      SpecialPowers.addPermission("storageAccessAPI", true, window.location.href).then(() => {
+        SpecialPowers.wrap(document).requestStorageAccess().then(() => {
+          executeTest();
+        });
       });
     });
   } else {