Have ScriptPromiseResolver on the Oilpan heap always.

Source/web/WebMIDIPermissionRequest.cpp

 /*
  * 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 20 matching lines @@
 #include "config.h"
 #include "public/web/WebMIDIPermissionRequest.h"
 
 #include "modules/webmidi/MIDIAccessInitializer.h"
 #include "platform/weborigin/SecurityOrigin.h"
 #include "public/platform/WebSecurityOrigin.h"
 
 namespace blink {
 
 WebMIDIPermissionRequest::WebMIDIPermissionRequest(MIDIAccessInitializer* initializer)
-    : m_initializer(initializer)
+    : m_private(initializer)
 {
 }
 
+void WebMIDIPermissionRequest::reset()
+{
+    m_private.reset();
+}
+
+void WebMIDIPermissionRequest::assign(const WebMIDIPermissionRequest& other)
+{
+    m_private = other.m_private;
+}
+
 bool WebMIDIPermissionRequest::equals(const WebMIDIPermissionRequest& n) const
 {
-    return m_initializer == n.m_initializer;
+    return m_private.get() == n.m_private.get();
 }
 
 WebSecurityOrigin WebMIDIPermissionRequest::securityOrigin() const
 {
-    return WebSecurityOrigin(m_initializer->securityOrigin());
+    return WebSecurityOrigin(m_private->securityOrigin());
 }
 
 void WebMIDIPermissionRequest::setIsAllowed(bool allowed)
 {
-    m_initializer->resolveSysexPermission(allowed);
+    m_private->resolveSysexPermission(allowed);
 }
 
 } // namespace blink