Ensure that all descriptors have a valid enumeration index, and replace NextEnumIndex with LastAdde…

src/ia32/macro-assembler-ia32.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2883 matching lines @@
   mov(ebx, FieldOperand(ecx, HeapObject::kMapOffset));
   mov(edx, FieldOperand(ebx, Map::kInstanceDescriptorsOrBackPointerOffset));
   CheckMap(edx,
            isolate()->factory()->fixed_array_map(),
            call_runtime,
            DONT_DO_SMI_CHECK);
 
   // Check that there is an enum cache in the non-empty instance
   // descriptors (edx).  This is the case if the next enumeration
   // index field does not contain a smi.
-  mov(edx, FieldOperand(edx, DescriptorArray::kEnumerationIndexOffset));
+  mov(edx, FieldOperand(edx, DescriptorArray::kLastAddedOffset));
   JumpIfSmi(edx, call_runtime);
 
   // For all objects but the receiver, check that the cache is empty.
   Label check_prototype;
   cmp(ecx, eax);
   j(equal, &check_prototype, Label::kNear);
   mov(edx, FieldOperand(edx, DescriptorArray::kEnumCacheBridgeCacheOffset));
   cmp(edx, isolate()->factory()->empty_fixed_array());
   j(not_equal, call_runtime);
 
   // Load the prototype from the map and loop if non-null.
   bind(&check_prototype);
   mov(ecx, FieldOperand(ebx, Map::kPrototypeOffset));
   cmp(ecx, isolate()->factory()->null_value());
   j(not_equal, &next);
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32