Rework dispatchEvent so it is consistent for isTrusted support.

Source/core/events/EventTarget.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 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  *           (C) 2007, 2008 Nikolas Zimmermann <zimmermann@kde.org>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ skipping 164 matching lines @@
         return false;
     }
     if (event->isBeingDispatched()) {
         exceptionState.throwDOMException(InvalidStateError, "The event is already being dispatched.");
         return false;
     }
 
     if (!executionContext())
         return false;
 
-    return dispatchEvent(event);
+    return dispatchEventInternal(event);
 }
 
 bool EventTarget::dispatchEvent(PassRefPtrWillBeRawPtr<Event> event)
 {
+    return dispatchEventInternal(event);
+}
+
+bool EventTarget::dispatchEventInternal(PassRefPtrWillBeRawPtr<Event> event)
+{
     event->setTarget(this);
     event->setCurrentTarget(this);
     event->setEventPhase(Event::AT_TARGET);
     bool defaultWasNotPrevented = fireEventListeners(event.get());
     event->setEventPhase(0);
     return defaultWasNotPrevented;
 }
 
 void EventTarget::uncaughtExceptionInEventHandler()
 {
@@ skipping 178 matching lines @@
     // they have one less listener to invoke.
     if (d->firingEventIterators) {
         for (size_t i = 0; i < d->firingEventIterators->size(); ++i) {
             d->firingEventIterators->at(i).iterator = 0;
             d->firingEventIterators->at(i).end = 0;
         }
     }
 }
 
 } // namespace blink