Crashed at ImageEventListener::cast & ConditionEventListener::cast

Source/core/events/RegisteredEventListener.h

Index: Source/core/events/RegisteredEventListener.h
diff --git a/Source/core/events/RegisteredEventListener.h b/Source/core/events/RegisteredEventListener.h
index 8916ed28576a2e642d37b365b16419d501d38a9d..d9592c10d4ae14532f104add61a84f07a105f6b8 100644
--- a/Source/core/events/RegisteredEventListener.h
+++ b/Source/core/events/RegisteredEventListener.h
@@ -43,6 +43,8 @@ namespace blink {
 
     inline bool operator==(const RegisteredEventListener& a, const RegisteredEventListener& b)
     {
+        ASSERT(a.listener);
+        ASSERT(b.listener);
         return *a.listener == *b.listener && a.useCapture == b.useCapture;
     }