Fix a DCHECK failure on an exception message

A DCHECK in LookupIterator::name hits when we add a indexed property,
as it requires a named property.
This replaces it with GetName to avoid the failure.

Bug: chromium:959727
Change-Id: I1e98b313ec9257db80460a34d691016acbceb3c9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1597372
Commit-Queue: Taiju Tsuiki <tzik@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61358}

src/objects.cc

@@ -2571,7 +2571,7 @@ Maybe<bool> Object::SetProperty(LookupIterator* it, Handle<Object> value,
       (GetShouldThrow(it->isolate(), should_throw) ==
        ShouldThrow::kThrowOnError)) {
     it->isolate()->Throw(*it->isolate()->factory()->NewReferenceError(
-        MessageTemplate::kNotDefined, it->name()));
+        MessageTemplate::kNotDefined, it->GetName()));
     return Nothing<bool>();
   }
 

test/mjsunit/regress/regress-crbug-959727.js

+// Copyright 2019 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+'use strict';
+let r = Realm.createAllowCrossRealmAccess();
+Realm.detachGlobal(r);
+try {
+  Realm.global(r)[1] = 0;
+} catch (e) {
+}