Revert 12609 (Allow partial scanning of large arrays)

src/spaces.cc

 // Copyright 2011 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 2660 matching lines @@
   for (uintptr_t key = base; key <= limit; key++) {
     HashMap::Entry* entry = chunk_map_.Lookup(reinterpret_cast<void*>(key),
                                               static_cast<uint32_t>(key),
                                               true);
     ASSERT(entry != NULL);
     entry->value = page;
   }
 
   HeapObject* object = page->GetObject();
 
-  // Make the object consistent so the large object space can be traversed.
+#ifdef DEBUG
+  // Make the object consistent so the heap can be vefified in OldSpaceStep.
   reinterpret_cast<Object**>(object->address())[0] =
       heap()->fixed_array_map();
   reinterpret_cast<Object**>(object->address())[1] = Smi::FromInt(0);
+#endif
 
   heap()->incremental_marking()->OldSpaceStep(object_size);
   return object;
 }
 
 
 // GC support
 MaybeObject* LargeObjectSpace::FindObject(Address a) {
   LargePage* page = FindPage(a);
   if (page != NULL) {
@@ skipping 190 matching lines @@
     object->ShortPrint();
     PrintF("\n");
   }
   printf(" --------------------------------------\n");
   printf(" Marked: %x, LiveCount: %x\n", mark_size, LiveBytes());
 }
 
 #endif  // DEBUG
 
 } }  // namespace v8::internal