Have ScriptPromiseResolver on the Oilpan heap always.

Source/modules/presentation/PresentationSessionClientCallbacks.h

 // Copyright 2015 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 PresentationSessionClientCallbacks_h
 #define PresentationSessionClientCallbacks_h
 
 #include "platform/heap/Handle.h"
 #include "public/platform/modules/presentation/WebPresentationClient.h"
 #include "wtf/Noncopyable.h"
-#include "wtf/PassRefPtr.h"
-#include "wtf/RefPtr.h"
 
 namespace blink {
 
 class Presentation;
 class ScriptPromiseResolver;
 
 // The implementation of the WebCallbacks interface passed to the embedder to
 // get the result of start/joinSession() calls. Will in its turn resolve the
 // corresponding Promise given to the frame.
 // When creating the session succeeds, onSuccess() is invoked with the
 // implementation of the WebPresentationSessionClient interface. If creating the
 // session fails, onError() is invoked with the implementation of the
 // WebPresentationError interface.
 // Owned by the receiver of the callback and must be deleted after use.
 class PresentationSessionClientCallbacks final : public WebPresentationSessionClientCallbacks {
     WTF_MAKE_NONCOPYABLE(PresentationSessionClientCallbacks);
 public:
-    PresentationSessionClientCallbacks(PassRefPtrWillBeRawPtr<ScriptPromiseResolver>, Presentation*);
+    PresentationSessionClientCallbacks(ScriptPromiseResolver*, Presentation*);
     ~PresentationSessionClientCallbacks() override;
 
     // WebPresentationSessionClientCallbacks implementation.
     void onSuccess(WebPresentationSessionClient*) override;
     void onError(WebPresentationError*) override;
 
 private:
-    RefPtrWillBePersistent<ScriptPromiseResolver> m_resolver;
+    Persistent<ScriptPromiseResolver> m_resolver;
     Persistent<Presentation> m_presentation;
 };
 
 } // namespace blink
 
 #endif // PresentationSessionClientCallbacks_h