Cleanup element normalization logic

src/isolate.cc

 // Copyright 2012 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.
 
 #include <stdlib.h>
 
 #include <fstream>  // NOLINT(readability/streams)
 #include <sstream>
 
 #include "src/v8.h"
@@ skipping 2419 matching lines @@
     // shouldn't be performed.
     return cell_reports_intact;
   }
 
   // Check that the array prototype hasn't been altered WRT empty elements.
   if (root_array_map->prototype() != initial_array_proto) {
     DCHECK_EQ(false, cell_reports_intact);
     return cell_reports_intact;
   }
 
-  if (initial_array_proto->elements() != heap()->empty_fixed_array()) {
+  FixedArrayBase* elements = initial_array_proto->elements();
+  if (elements != heap()->empty_fixed_array() &&
+      elements != heap()->empty_slow_element_dictionary()) {
     DCHECK_EQ(false, cell_reports_intact);
     return cell_reports_intact;
   }
 
   // Check that the object prototype hasn't been altered WRT empty elements.
   PrototypeIterator iter(this, initial_array_proto);
   if (iter.IsAtEnd() || iter.GetCurrent() != initial_object_proto) {
     DCHECK_EQ(false, cell_reports_intact);
     return cell_reports_intact;
   }
-  if (initial_object_proto->elements() != heap()->empty_fixed_array()) {
+
+  elements = initial_object_proto->elements();
+  if (elements != heap()->empty_fixed_array() &&
+      elements != heap()->empty_slow_element_dictionary()) {
     DCHECK_EQ(false, cell_reports_intact);
     return cell_reports_intact;
   }
 
   iter.Advance();
   if (!iter.IsAtEnd()) {
     DCHECK_EQ(false, cell_reports_intact);
     return cell_reports_intact;
   }
 
@@ skipping 345 matching lines @@
   // Then check whether this scope intercepts.
   if ((flag & intercept_mask_)) {
     intercepted_flags_ |= flag;
     return true;
   }
   return false;
 }
 
 }  // namespace internal
 }  // namespace v8