Actually hook up ServiceWorkerRegistration.showNotification()

Source/bindings/core/v8/CallbackPromiseAdapter.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 152 matching lines @@
             return;
         }
         m_resolver->reject(T::take(m_resolver.get(), error));
     }
 
 private:
     RefPtr<ScriptPromiseResolver> m_resolver;
     WTF_MAKE_NONCOPYABLE(CallbackPromiseAdapter);
 };
 
+template<>
+class CallbackPromiseAdapter<void, void> final : public blink::WebCallbacks<void, void> {
+public:
+    explicit CallbackPromiseAdapter(PassRefPtr<ScriptPromiseResolver> resolver)
+        : m_resolver(resolver)
+    {
+        ASSERT(m_resolver);
+    }
+    virtual ~CallbackPromiseAdapter() { }
+
+    virtual void onSuccess() override
+    {
+        if (!m_resolver->executionContext() || m_resolver->executionContext()->activeDOMObjectsAreStopped())
+            return;
+        m_resolver->resolve();
+    }
+
+    virtual void onError() override
+    {
+        if (!m_resolver->executionContext() || m_resolver->executionContext()->activeDOMObjectsAreStopped())
+            return;
+        m_resolver->reject();
+    }
+
+private:
+    RefPtr<ScriptPromiseResolver> m_resolver;
+    WTF_MAKE_NONCOPYABLE(CallbackPromiseAdapter);
+};
+
 } // namespace blink
 
 #endif