WebServiceWorkerProxy instances can be unwrapped to ServiceWorkers.

Source/modules/serviceworkers/ServiceWorker.h

Index: Source/modules/serviceworkers/ServiceWorker.h
diff --git a/Source/modules/serviceworkers/ServiceWorker.h b/Source/modules/serviceworkers/ServiceWorker.h
index 9e49f4dcef7f107ba6b0269be71d26860225522b..111e02de8ee4a3df5522e9c7255880d608c7bbaa 100644
--- a/Source/modules/serviceworkers/ServiceWorker.h
+++ b/Source/modules/serviceworkers/ServiceWorker.h
@@ -42,10 +42,6 @@
 #include "wtf/PassRefPtr.h"
 #include "wtf/RefCounted.h"
 
-namespace blink {
-class WebServiceWorker;
-}
-
 namespace WebCore {
 
 class ScriptState;
@@ -64,6 +60,8 @@ public:
     typedef blink::WebServiceWorker WebType;
     static PassRefPtr<ServiceWorker> from(ScriptPromiseResolverWithContext*, WebType* worker);
 
+    static PassRefPtr<ServiceWorker> from(ScriptState*, WebType*);
+
     void postMessage(PassRefPtr<SerializedScriptValue> message, const MessagePortArray*, ExceptionState&);
 
     String scope() const;