Make ServiceWorker an ActiveDOMObject

LayoutTests/virtual/serviceworker/http/tests/serviceworker/service-worker-gc-expected.txt

Index: LayoutTests/virtual/serviceworker/http/tests/serviceworker/service-worker-gc-expected.txt
diff --git a/LayoutTests/virtual/serviceworker/http/tests/serviceworker/service-worker-gc-expected.txt b/LayoutTests/virtual/serviceworker/http/tests/serviceworker/service-worker-gc-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..d92607af890380d387c54f6f4e259fac95923b46
--- /dev/null
+++ b/LayoutTests/virtual/serviceworker/http/tests/serviceworker/service-worker-gc-expected.txt
@@ -0,0 +1,21 @@
+Test that a registered Service Worker with an event handler is not garbage collected
+
+On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
+
+
+Service Worker should not be gc'd in installing state
+PASS swObservation.wasCollected is false
+Service Worker should not be gc'd in installed state
+PASS swObservation.wasCollected is false
+Service Worker should not be gc'd after registration
+PASS swObservation.wasCollected is false
+Service Worker should not be gc'd in activating state
+PASS swObservation.wasCollected is false
+Service Worker should not be gc'd in active state
+PASS swObservation.wasCollected is false
+Service Worker should not leak after unregistration
+PASS swObservation.wasCollected is false
+PASS successfullyParsed is true
+
+TEST COMPLETE
+