The following layout test is flaky on Windows (Debug and Release):
The first resource load event is happening before the test harness calls 'dumpResourceLoadCallbacks', so it is not getting added to the URL cache. When we later attempt to look up the URL by identifier, it doesn't find it and we return (null).
@@ -1,5 +1,5 @@
resources/first-page.html - willSendRequest <NSURLRequest URL resources/first-page.html, main document URL resources/first-page.html, http method GET> redirectResponse (null)
-go-back-cached-main-resource.html - didFinishLoading
+<unknown> - didFinishLoading
resources/first-page.html - didReceiveResponse <NSURLResponse resources/first-page.html, http status code 0>
A similar bug is affecting fast/preloader/scan-body-from-head-script.html. The test often passes in Debug mode.