Make EventListener a callback interface

Source/bindings/tests/results/V8TestObject.h

Index: Source/bindings/tests/results/V8TestObject.h
diff --git a/Source/bindings/tests/results/V8TestObject.h b/Source/bindings/tests/results/V8TestObject.h
index 244554f909de142bdb1845dccab78afd6ac2c3d7..a6de18b4dee9ecdd7010ba1b2100e308ed850afc 100644
--- a/Source/bindings/tests/results/V8TestObject.h
+++ b/Source/bindings/tests/results/V8TestObject.h
@@ -45,7 +45,8 @@ public:
     static void constructorCallback(const v8::FunctionCallbackInfo<v8::Value>&);
     static void customAttrAttrGetterCustom(v8::Local<v8::String> name, const v8::PropertyCallbackInfo<v8::Value>&);
     static void customAttrAttrSetterCustom(v8::Local<v8::String> name, v8::Local<v8::Value>, const v8::PropertyCallbackInfo<void>&);
-    static const int internalFieldCount = v8DefaultWrapperInternalFieldCount + 0;
+    static const int eventListenerCacheIndex = v8DefaultWrapperInternalFieldCount + 0;
+    static const int internalFieldCount = v8DefaultWrapperInternalFieldCount + 1;
     static inline void* toInternalPointer(TestObj* impl)
     {
         return impl;