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

Source/bindings/tests/results/core/V8TestInterfaceConstructor.cpp

Index: Source/bindings/tests/results/core/V8TestInterfaceConstructor.cpp
diff --git a/Source/bindings/tests/results/core/V8TestInterfaceConstructor.cpp b/Source/bindings/tests/results/core/V8TestInterfaceConstructor.cpp
index f1d0bbfe655469f9871335de3a49a902ff00fda5..86281baab54d5c3863fb7315c026fd266d092387 100644
--- a/Source/bindings/tests/results/core/V8TestInterfaceConstructor.cpp
+++ b/Source/bindings/tests/results/core/V8TestInterfaceConstructor.cpp
@@ -304,7 +304,7 @@ v8::Local<v8::FunctionTemplate> V8TestInterfaceConstructorConstructor::domTempla
     result = v8::FunctionTemplate::New(isolate, V8TestInterfaceConstructorConstructorCallback);
     v8::Local<v8::ObjectTemplate> instanceTemplate = result->InstanceTemplate();
     instanceTemplate->SetInternalFieldCount(V8TestInterfaceConstructor::internalFieldCount);
-    result->SetClassName(v8AtomicString(isolate, "TestInterfaceConstructor"));
+    instanceTemplate->Set(v8::Symbol::GetToStringTag(isolate), v8AtomicString(isolate, "TestInterfaceConstructor"));
     result->Inherit(V8TestInterfaceConstructor::domTemplate(isolate));
     data->setDOMTemplate(&domTemplateKey, result);
     return result;
@@ -343,6 +343,10 @@ static void installV8TestInterfaceConstructorTemplate(v8::Local<v8::FunctionTemp
     v8::Local<v8::ObjectTemplate> prototypeTemplate = functionTemplate->PrototypeTemplate();
     ALLOW_UNUSED_LOCAL(prototypeTemplate);
 
+    instanceTemplate->Set(v8::Symbol::GetToStringTag(isolate), v8AtomicString(isolate, "TestInterfaceConstructor"));
+
+    prototypeTemplate->Set(v8::Symbol::GetToStringTag(isolate), v8AtomicString(isolate, "TestInterfaceConstructorPrototype"));
+
     // Custom toString template
     functionTemplate->Set(v8AtomicString(isolate, "toString"), V8PerIsolateData::from(isolate)->toStringTemplate());
 }