ServiceWorkerGlobalScope prototype chain should be immutable

ServiceWorkerGlobalScope prototype chain should be immutable
https://bugs.webkit.org/show_bug.cgi?id=180450

Reviewed by Youenn Fablet.

LayoutTests/imported/w3c:

Rebaseline test that no longer times out.

* web-platform-tests/service-workers/service-worker/interfaces-sw.https-expected.txt:

Source/WebCore:

ServiceWorkerGlobalScope prototype chain should be immutable, similarly
to what we do for DOMWindow. This is covered by a web-platform-test
which was timing out because it was successfuly overwriting the
ServiceWorkerGlobalScope prototype.

No new tests, rebaselined existing test.

* workers/DedicatedWorkerGlobalScope.idl:
* workers/WorkerGlobalScope.idl:
* workers/service/ServiceWorkerGlobalScope.idl:

LayoutTests:

* TestExpectations:
Unskip test that no longer times out.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@225566 268f45cc-cd09-0410-ab3c-d52691b4dbfc