Remove left-overs of PushSubscription.curve25519dh

Source/modules/push_messaging/PushSubscription.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef PushSubscription_h
 #define PushSubscription_h
 
 #include "bindings/core/v8/ScriptPromise.h"
 #include "bindings/core/v8/ScriptValue.h"
 #include "bindings/core/v8/ScriptWrappable.h"
@@ skipping 12 matching lines @@
 
 class PushSubscription final : public GarbageCollectedFinalized<PushSubscription>, public ScriptWrappable {
     DEFINE_WRAPPERTYPEINFO();
 public:
     static PushSubscription* take(ScriptPromiseResolver*, PassOwnPtr<WebPushSubscription>, ServiceWorkerRegistration*);
     static void dispose(WebPushSubscription* subscriptionRaw);
 
     virtual ~PushSubscription();
 
     KURL endpoint() const;
-    PassRefPtr<DOMArrayBuffer> curve25519dh() const;
 
     PassRefPtr<DOMArrayBuffer> getKey(const AtomicString& name) const;
     ScriptPromise unsubscribe(ScriptState*);
 
     ScriptValue toJSONForBinding(ScriptState*);
 
     DECLARE_TRACE();
 
 private:
     PushSubscription(const WebPushSubscription&, ServiceWorkerRegistration*);
 
     KURL m_endpoint;
     RefPtr<DOMArrayBuffer> m_curve25519dh;
 
     Member<ServiceWorkerRegistration> m_serviceWorkerRegistration;
 };
 
 } // namespace blink
 
 #endif // PushSubscription_h