ServiceWorker: throw when close() or terminate() called

Source/modules/serviceworkers/ServiceWorkerGlobalScope.idl

Index: Source/modules/serviceworkers/ServiceWorkerGlobalScope.idl
diff --git a/Source/modules/serviceworkers/ServiceWorkerGlobalScope.idl b/Source/modules/serviceworkers/ServiceWorkerGlobalScope.idl
index 73aa2df48f3b1a20fb99dc94118d5e9e5b8ca0aa..2b4ec9fe53dc672530ce7784e3633635daa4a46a 100644
--- a/Source/modules/serviceworkers/ServiceWorkerGlobalScope.idl
+++ b/Source/modules/serviceworkers/ServiceWorkerGlobalScope.idl
@@ -43,6 +43,8 @@
   [CallWith=ScriptState] Promise fetch(DOMString request, optional Dictionary requestInitDict);
   [CallWith=ScriptState] Promise fetch(Request request, optional Dictionary requestInitDict);
 
+  [RaisesException] void close();
+
   attribute EventHandler onactivate;
   attribute EventHandler onfetch;
   attribute EventHandler oninstall;