Fix receiver checks for v8::Function on a remote context.

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index 059ab0e8868c408c18ae52bf0b95b22274dd68ab..432c4b450858980f2eda3a85de280968213f45a5 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -4494,33 +4494,6 @@ bool v8::Object::SetPrototype(Local<Value> value) {
   return SetPrototype(context, value).FromMaybe(false);
 }
 
-static bool HasInstanceInGlobalProxy(i::JSGlobalProxy* global_proxy,
-                                     i::FunctionTemplateInfo* target_template) {
-  auto* constructor_object = global_proxy->map()->GetConstructor();
-  if (!constructor_object->IsJSFunction()) return false;
-
-  auto* constructor = i::JSFunction::cast(constructor_object);
-  if (!constructor->shared()->function_data()->IsFunctionTemplateInfo())
-    return false;
-
-  auto* proxy_constructor_template =
-      i::FunctionTemplateInfo::cast(constructor->shared()->function_data());
-  if (!proxy_constructor_template->prototype_template()->IsObjectTemplateInfo())
-    return false;
-
-  auto* global_template = i::ObjectTemplateInfo::cast(
-      proxy_constructor_template->prototype_template());
-  // Iterate through the chain of inheriting function templates to
-  // see if the required one occurs.
-  for (i::Object* type = global_template->constructor();
-       type->IsFunctionTemplateInfo();
-       type = i::FunctionTemplateInfo::cast(type)->parent_template()) {
-    if (type == target_template) return true;
-  }
-  // Didn't find the required type in the inheritance chain.
-  return false;
-}
-
 Local<Object> v8::Object::FindInstanceInPrototypeChain(
     v8::Local<FunctionTemplate> tmpl) {
   auto self = Utils::OpenHandle(this);
@@ -4529,16 +4502,7 @@ Local<Object> v8::Object::FindInstanceInPrototypeChain(
   auto tmpl_info = *Utils::OpenHandle(*tmpl);
   while (!tmpl_info->IsTemplateFor(iter.GetCurrent<i::JSObject>())) {
     iter.Advance();
-    if (iter.IsAtEnd()) {
-      // Normally, a standard prototype walk is sufficient; however, global
-      // proxies aren't directly constructed with the supplied template.
-      // Normally, this is not a problem, because the prototype chain includes
-      // the global object; however, a remote context has no global object.
-      if (self->IsJSGlobalProxy() &&
-          HasInstanceInGlobalProxy(i::JSGlobalProxy::cast(*self), tmpl_info))
-        return Utils::ToLocal(self);
-      return Local<Object>();
-    }
+    if (iter.IsAtEnd()) return Local<Object>();
     if (!iter.GetCurrent()->IsJSObject()) return Local<Object>();
   }
   // IsTemplateFor() ensures that iter.GetCurrent() can't be a Proxy here.
@@ -6605,12 +6569,13 @@ bool FunctionTemplate::HasInstance(v8::Local<v8::Value> value) {
     return true;
   }
   if (obj->IsJSGlobalProxy()) {
-    auto* global_proxy = i::JSGlobalProxy::cast(*obj);
-    // For global proxies, check the constructor's prototype instead. Remote
-    // global proxies have no global object to perform instance checks on, but
-    // the constructor's prototype's constructor corresponds to the original
-    // template used to create the context.
-    return HasInstanceInGlobalProxy(global_proxy, *self);
+    // If it's a global proxy, then test with the global object. Note that the
+    // inner global object may not necessarily be a JSGlobalObject.
+    i::PrototypeIterator iter(i::JSObject::cast(*obj)->map());
+    // The global proxy should always have a prototype, as it is a bug to call
+    // this on a detached JSGlobalProxy.
+    DCHECK(!iter.IsAtEnd());
+    return self->IsTemplateFor(iter.GetCurrent<i::JSObject>());
   }
   return false;
 }