Oilpan: Move the EventListener hierarchy to Oilpan's heap

Source/core/frame/EventHandlerRegistry.cpp

Index: Source/core/frame/EventHandlerRegistry.cpp
diff --git a/Source/core/frame/EventHandlerRegistry.cpp b/Source/core/frame/EventHandlerRegistry.cpp
index 45f5d67e4de779623b8a5503290287c62802d144..f04362b3495eb2568fcb8ee9e652aaa06490bf9c 100644
--- a/Source/core/frame/EventHandlerRegistry.cpp
+++ b/Source/core/frame/EventHandlerRegistry.cpp
@@ -161,7 +161,10 @@ void EventHandlerRegistry::didMoveIntoFrameHost(EventTarget& target)
         EventHandlerClass handlerClass;
         if (!eventTypeToClass(eventTypes[i], &handlerClass))
             continue;
-        for (unsigned count = target.getEventListeners(eventTypes[i]).size(); count > 0; --count)
+        EventListenerVector* listeners = target.getEventListeners(eventTypes[i]);
+        if (!listeners)
+            continue;
+        for (unsigned count = listeners->size(); count > 0; --count)
             didAddEventHandler(target, handlerClass);
     }
 }