Oilpan: dispose ServiceWorker (and registration) objects earlier.

Source/modules/serviceworkers/ServiceWorkerRegistration.h

Index: Source/modules/serviceworkers/ServiceWorkerRegistration.h
diff --git a/Source/modules/serviceworkers/ServiceWorkerRegistration.h b/Source/modules/serviceworkers/ServiceWorkerRegistration.h
index 0cf67c255bc50426162cca7b14412622f83f4327..62ae742a0514c5ad5170ce7b04ffdb612851688d 100644
--- a/Source/modules/serviceworkers/ServiceWorkerRegistration.h
+++ b/Source/modules/serviceworkers/ServiceWorkerRegistration.h
@@ -31,6 +31,7 @@ class ServiceWorkerRegistration final
     DEFINE_WRAPPERTYPEINFO();
     DEFINE_EVENT_TARGET_REFCOUNTING_WILL_BE_REMOVED(RefCountedGarbageCollected<ServiceWorkerRegistration>);
     USING_GARBAGE_COLLECTED_MIXIN(ServiceWorkerRegistration);
+    USING_PRE_FINALIZER(ServiceWorkerRegistration, dispose);
 public:
     // EventTarget overrides.
     virtual const AtomicString& interfaceName() const override;
@@ -60,6 +61,7 @@ public:
 
     DEFINE_ATTRIBUTE_EVENT_LISTENER(updatefound);
 
+    virtual ~ServiceWorkerRegistration() override;
     virtual void trace(Visitor*) override;
 
 private:
@@ -70,6 +72,8 @@ private:
     virtual bool hasPendingActivity() const override;
     virtual void stop() override;
 
+    void dispose();
+
     OwnPtr<WebServiceWorkerRegistration> m_outerRegistration;
     WebServiceWorkerProvider* m_provider;
     RefPtrWillBeMember<ServiceWorker> m_installing;