IDL: Remove holder lookup in attribute_getter macro

Source/bindings/tests/results/V8TestObject.cpp

Index: Source/bindings/tests/results/V8TestObject.cpp
diff --git a/Source/bindings/tests/results/V8TestObject.cpp b/Source/bindings/tests/results/V8TestObject.cpp
index 80e093a6d7aeee10e688f0c4ad31197d2b3c3458..9a9b3183de9e11d8a5e5b287113f882ebd09946f 100644
--- a/Source/bindings/tests/results/V8TestObject.cpp
+++ b/Source/bindings/tests/results/V8TestObject.cpp
@@ -4579,9 +4579,7 @@ static void urlStringAttributeAttributeSetterCallback(v8::Local<v8::String>, v8:
 
 static void unforgeableLongAttributeAttributeGetter(const v8::PropertyCallbackInfo<v8::Value>& info)
 {
-    v8::Handle<v8::Object> holder = V8TestObject::findInstanceInPrototypeChain(info.This(), info.GetIsolate());
-    if (holder.IsEmpty())
-        return;
+    v8::Handle<v8::Object> holder = info.Holder();
     TestObject* impl = V8TestObject::toNative(holder);
     v8SetReturnValueInt(info, impl->unforgeableLongAttribute());
 }