[iOS WK2] Layout Test imported/w3c/web-platform-tests/service-workers/service-worker...

[iOS WK2] Layout Test imported/w3c/web-platform-tests/service-workers/service-worker/update-after-navigation-fetch-event.https.html is a flaky failure
https://bugs.webkit.org/show_bug.cgi?id=181499
<rdar://problem/36443428>

Reviewed by Youenn Fablet.

Source/WebCore:

After resolving a registration promise, we send an IPC back to the StorageProcess
for synchronization purposes, to make sure the registration does not get updated
before the promise's JS code has been executed. However, resolving a promise
schedules a microtask to run the JS and we would therefore send the IPC back too
early, thus causing flakiness. We now only send the IPC back back only after that
microtask has run and the JS has been executed.

* bindings/js/JSDOMPromiseDeferred.cpp:
(WebCore::DeferredPromise::callFunction):
(WebCore::DeferredPromise::whenSettled):
* bindings/js/JSDOMPromiseDeferred.h:
* workers/service/ServiceWorkerContainer.cpp:
(WebCore::ServiceWorkerContainer::jobResolvedWithRegistration):

LayoutTests:

Unskip test that should no longer be flaky.

* platform/ios/TestExpectations:

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@232156 268f45cc-cd09-0410-ab3c-d52691b4dbfc