Oilpan: Fix tracing of events through XMLHttpRequestProgressEventThrottle.

Source/core/html/HTMLFormElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 417 matching lines @@
 void HTMLFormElement::requestAutocomplete()
 {
     if (!document().frame() || !shouldAutocomplete() || !UserGestureIndicator::processingUserGesture())
         finishRequestAutocomplete(AutocompleteResultErrorDisabled);
     else
         document().frame()->loader().client()->didRequestAutocomplete(this);
 }
 
 void HTMLFormElement::finishRequestAutocomplete(AutocompleteResult result)
 {
-    RefPtrWillBeRawPtr<Event> event;
+    RefPtrWillBeRawPtr<Event> event = nullptr;
     if (result == AutocompleteResultSuccess)
         event = Event::create(EventTypeNames::autocomplete);
     else if (result == AutocompleteResultErrorDisabled)
         event = AutocompleteErrorEvent::create("disabled");
     else if (result == AutocompleteResultErrorCancel)
         event = AutocompleteErrorEvent::create("cancel");
     else if (result == AutocompleteResultErrorInvalid)
         event = AutocompleteErrorEvent::create("invalid");
 
     event->setTarget(this);
@@ skipping 326 matching lines @@
 }
 
 void HTMLFormElement::setDemoted(bool demoted)
 {
     if (demoted)
         UseCounter::count(document(), UseCounter::DemotedFormElement);
     m_wasDemoted = demoted;
 }
 
 } // namespace