REGRESSION: [ Mac ] http/tests/storageAccess/request-and-grant-access-then-detach-should-not-have-access-database.html is a flaky failure

[Truitt Savell]

http/tests/storageAccess/request-and-grant-access-then-detach-should-not-have-access-database.html

This test became a flaky failure recently. The diff shows the test failing to present output. 

I can reproduce a failure locally by running the test in iterations but the diff is not the same.

history:
https://results.webkit.org/?suite=layout-tests&test=http%2Ftests%2FstorageAccess%2Frequest-and-grant-access-then-detach-should-not-have-access-database.html

Diff
--- /Volumes/Data/slave/mojave-release-tests-wk2/build/layout-test-results/http/tests/storageAccess/request-and-grant-access-then-detach-should-not-have-access-database-expected.txt
+++ /Volumes/Data/slave/mojave-release-tests-wk2/build/layout-test-results/http/tests/storageAccess/request-and-grant-access-then-detach-should-not-have-access-database-actual.txt
@@ -1,12 +1,2 @@
-Tests that a cross-origin iframe from a prevalent domain that is granted storage access and then is detached from the DOM does not have storage access.
-
-On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
 
 
-PASS Storage access was granted. document.cookie == firstPartyCookie=value, cookies seen server-side == {"firstPartyCookie":"value"}
-PASS There is a storage access entry for localhost.
-PASS There is no storage access entry for localhost after iframe detach.
-PASS successfullyParsed is true
-
-TEST COMPLETE
-

[Radar WebKit Bug Importer]

<rdar://problem/59868408>