Make sure we correctly dispatch custom events having the same names as unprefixed animations events

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 249 matching lines @@
     if (!d)
         return true;
 
     EventListenerVector* legacyListenersVector = 0;
     AtomicString legacyTypeName = legacyType(event);
     if (!legacyTypeName.isEmpty())
         legacyListenersVector = d->eventListenerMap.find(legacyTypeName);
 
     EventListenerVector* listenersVector = d->eventListenerMap.find(event->type());
     if (!RuntimeEnabledFeatures::cssAnimationUnprefixedEnabled() && (event->type() == EventTypeNames::animationiteration || event->type() == EventTypeNames::animationend
-        || event->type() == EventTypeNames::animationstart))
+        || event->type() == EventTypeNames::animationstart)
+        // Some code out-there uses custom events to dispatch unprefixed animation events manually,
+        // we can safely remove all this block when cssAnimationUnprefixedEnabled is always on, this
+        // is really a special case. DO NOT ADD MORE EVENTS HERE.
+        && event->interfaceName() != EventNames::CustomEvent)
         listenersVector = 0;
 
     if (listenersVector) {
         fireEventListeners(event, d, *listenersVector);
     } else if (legacyListenersVector) {
         AtomicString unprefixedTypeName = event->type();
         event->setType(legacyTypeName);
         fireEventListeners(event, d, *legacyListenersVector);
         event->setType(unprefixedTypeName);
     }
@@ skipping 86 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 WebCore