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

Source/bindings/tests/results/core/V8TestInterfaceEventInitConstructor.cpp

Index: Source/bindings/tests/results/core/V8TestInterfaceEventInitConstructor.cpp
diff --git a/Source/bindings/tests/results/core/V8TestInterfaceEventInitConstructor.cpp b/Source/bindings/tests/results/core/V8TestInterfaceEventInitConstructor.cpp
index 1d422469c01deeed825fe7c76cea47736afa38a1..ee2f6b3eadb7bf5733aea38aa5816cff17093a6f 100644
--- a/Source/bindings/tests/results/core/V8TestInterfaceEventInitConstructor.cpp
+++ b/Source/bindings/tests/results/core/V8TestInterfaceEventInitConstructor.cpp
@@ -112,6 +112,10 @@ static void installV8TestInterfaceEventInitConstructorTemplate(v8::Local<v8::Fun
     v8::Local<v8::ObjectTemplate> prototypeTemplate = functionTemplate->PrototypeTemplate();
     ALLOW_UNUSED_LOCAL(prototypeTemplate);
 
+    instanceTemplate->Set(v8::Symbol::GetToStringTag(isolate), v8AtomicString(isolate, "TestInterfaceEventInitConstructor"));
+
+    prototypeTemplate->Set(v8::Symbol::GetToStringTag(isolate), v8AtomicString(isolate, "TestInterfaceEventInitConstructorPrototype"));
+
     // Custom toString template
     functionTemplate->Set(v8AtomicString(isolate, "toString"), V8PerIsolateData::from(isolate)->toStringTemplate());
 }