ServiceWorker: unregister's scope argument should be optional

Source/modules/serviceworkers/ServiceWorkerContainer.idl

Index: Source/modules/serviceworkers/ServiceWorkerContainer.idl
diff --git a/Source/modules/serviceworkers/ServiceWorkerContainer.idl b/Source/modules/serviceworkers/ServiceWorkerContainer.idl
index 4dda7cd4e03927326dfe568e96d8a1d308fb1926..ade5d591ab63cda196c9e545cc5b346906d0c55c 100644
--- a/Source/modules/serviceworkers/ServiceWorkerContainer.idl
+++ b/Source/modules/serviceworkers/ServiceWorkerContainer.idl
@@ -41,5 +41,5 @@
     [CallWith=ScriptState] readonly attribute Promise ready;
 
     [CallWith=ScriptState, ImplementedAs=registerServiceWorker] Promise register(ScalarValueString url, optional Dictionary options);
-    [CallWith=ScriptState, ImplementedAs=unregisterServiceWorker] Promise unregister(ScalarValueString scope);
+    [CallWith=ScriptState, ImplementedAs=unregisterServiceWorker] Promise unregister(optional ScalarValueString scope = "/*");
 };