Remove incorrect dcheck from map updater.

Bug: chromium:933179
Change-Id: I511dfa7c060fd3f4e4b59c199a27a69d4cf81f97
Reviewed-on: https://chromium-review.googlesource.com/c/1477275Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59705}

src/map-updater.cc

@@ -367,7 +367,6 @@ MapUpdater::State MapUpdater::FindRootMap() {
 
     // Modify root map in-place.
     if (FLAG_modify_map_inplace && new_constness_ != old_details.constness()) {
-      DCHECK(old_map_->is_stable());
       DCHECK(IsGeneralizableTo(old_details.constness(), new_constness_));
       GeneralizeField(old_map_, modified_descriptor_, new_constness_,
                       old_details.representation(),

test/mjsunit/regress/regress-933179.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.
+
+var o = { ...{ length : 1 } };
+
+o.x = 1;
+delete o.x;
+
+o.length = 2;