[DO NOT LAND] Set @@toStringTag for DOM object prototypes

Source/bindings/tests/results/core/V8TestInterfaceNamedConstructor.cpp

Index: Source/bindings/tests/results/core/V8TestInterfaceNamedConstructor.cpp
diff --git a/Source/bindings/tests/results/core/V8TestInterfaceNamedConstructor.cpp b/Source/bindings/tests/results/core/V8TestInterfaceNamedConstructor.cpp
index 8d17eabd5e5a9947729b2ca954f83fd95b4b71d8..d8c7654998b98b78bfa931854081d4c41474159c 100644
--- a/Source/bindings/tests/results/core/V8TestInterfaceNamedConstructor.cpp
+++ b/Source/bindings/tests/results/core/V8TestInterfaceNamedConstructor.cpp
@@ -155,7 +155,7 @@ v8::Local<v8::FunctionTemplate> V8TestInterfaceNamedConstructorConstructor::domT
     result = v8::FunctionTemplate::New(isolate, V8TestInterfaceNamedConstructorConstructorCallback);
     v8::Local<v8::ObjectTemplate> instanceTemplate = result->InstanceTemplate();
     instanceTemplate->SetInternalFieldCount(V8TestInterfaceNamedConstructor::internalFieldCount);
-    result->SetClassName(v8AtomicString(isolate, "TestInterfaceNamedConstructor"));
+    instanceTemplate->Set(v8::Symbol::GetToStringTag(isolate), v8AtomicString(isolate, "TestInterfaceNamedConstructor"));
     result->Inherit(V8TestInterfaceNamedConstructor::domTemplate(isolate));
     data->setDOMTemplate(&domTemplateKey, result);
     return result;
@@ -175,6 +175,10 @@ static void installV8TestInterfaceNamedConstructorTemplate(v8::Local<v8::Functio
     v8::Local<v8::ObjectTemplate> prototypeTemplate = functionTemplate->PrototypeTemplate();
     ALLOW_UNUSED_LOCAL(prototypeTemplate);
 
+    instanceTemplate->Set(v8::Symbol::GetToStringTag(isolate), v8AtomicString(isolate, "TestInterfaceNamedConstructor"));
+
+    prototypeTemplate->Set(v8::Symbol::GetToStringTag(isolate), v8AtomicString(isolate, "TestInterfaceNamedConstructorPrototype"));
+
     // Custom toString template
     functionTemplate->Set(v8AtomicString(isolate, "toString"), V8PerIsolateData::from(isolate)->toStringTemplate());
 }