Install ConstructNonConstructable as construct stub for non-constructables.

src/runtime/runtime-object.cc

Index: src/runtime/runtime-object.cc
diff --git a/src/runtime/runtime-object.cc b/src/runtime/runtime-object.cc
index 51550df70deacab91da3bcf5b9f48c05ba75b2b3..c849e5b7f2abaff45089f086616f1eb69ff35b9b 100644
--- a/src/runtime/runtime-object.cc
+++ b/src/runtime/runtime-object.cc
@@ -1044,11 +1044,7 @@ RUNTIME_FUNCTION(Runtime_NewObject) {
   CONVERT_ARG_HANDLE_CHECKED(JSFunction, constructor, 0);
   CONVERT_ARG_HANDLE_CHECKED(JSReceiver, new_target, 1);
 
-  // TODO(verwaest): Make sure |constructor| is guaranteed to be a constructor.
-  if (!constructor->IsConstructor()) {
-    THROW_NEW_ERROR_RETURN_FAILURE(
-        isolate, NewTypeError(MessageTemplate::kNotConstructor, constructor));
-  }
+  DCHECK(constructor->IsConstructor());
 
   // If called through new, new.target can be:
   // - a subclass of constructor,