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

Source/bindings/tests/results/core/V8TestTypedefs.cpp

Index: Source/bindings/tests/results/core/V8TestTypedefs.cpp
diff --git a/Source/bindings/tests/results/core/V8TestTypedefs.cpp b/Source/bindings/tests/results/core/V8TestTypedefs.cpp
index 509f9b16851e51a8ecd59dcc95a238855b0a115b..8888b32439a37d66adb01604795d8098f0c338cd 100644
--- a/Source/bindings/tests/results/core/V8TestTypedefs.cpp
+++ b/Source/bindings/tests/results/core/V8TestTypedefs.cpp
@@ -358,6 +358,10 @@ static void installV8TestTypedefsTemplate(v8::Local<v8::FunctionTemplate> functi
     v8::Local<v8::ObjectTemplate> prototypeTemplate = functionTemplate->PrototypeTemplate();
     ALLOW_UNUSED_LOCAL(prototypeTemplate);
 
+    instanceTemplate->Set(v8::Symbol::GetToStringTag(isolate), v8AtomicString(isolate, "TestTypedefs"));
+
+    prototypeTemplate->Set(v8::Symbol::GetToStringTag(isolate), v8AtomicString(isolate, "TestTypedefsPrototype"));
+
     // Custom toString template
     functionTemplate->Set(v8AtomicString(isolate, "toString"), V8PerIsolateData::from(isolate)->toStringTemplate());
 }