Have ScriptPromiseResolver on the Oilpan heap always.

Source/modules/push_messaging/PushSubscription.cpp

 // 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.
 
 #include "config.h"
 #include "modules/push_messaging/PushSubscription.h"
 
 #include "bindings/core/v8/CallbackPromiseAdapter.h"
 #include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "bindings/core/v8/V8ObjectBuilder.h"
@@ skipping 34 matching lines @@
     return m_endpoint;
 }
 
 PassRefPtr<DOMArrayBuffer> PushSubscription::curve25519dh() const
 {
     return m_curve25519dh;
 }
 
 ScriptPromise PushSubscription::unsubscribe(ScriptState* scriptState)
 {
-    RefPtrWillBeRawPtr<ScriptPromiseResolver> resolver = ScriptPromiseResolver::create(scriptState);
+    ScriptPromiseResolver* resolver = ScriptPromiseResolver::create(scriptState);
     ScriptPromise promise = resolver->promise();
 
     WebPushProvider* webPushProvider = Platform::current()->pushProvider();
     ASSERT(webPushProvider);
 
     webPushProvider->unsubscribe(m_serviceWorkerRegistration->webRegistration(), new CallbackPromiseAdapter<bool, PushError>(resolver));
     return promise;
 }
 
 ScriptValue PushSubscription::toJSONForBinding(ScriptState* scriptState)
 {
     V8ObjectBuilder result(scriptState);
     result.addString("endpoint", endpoint());
 
     // TODO(peter): Include |curve25519dh| in the serialized JSON blob if the intended
     // serialization behavior gets defined in the spec.
 
     return result.scriptValue();
 }
 
 DEFINE_TRACE(PushSubscription)
 {
     visitor->trace(m_serviceWorkerRegistration);
 }
 
 } // namespace blink