Keep maps when resetting elements.

src/objects-inl.h

 // 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.
 //
 // Review notes:
 //
 // - The use of macros in these inline functions may seem superfluous
 // but it is absolutely needed to make sure gcc generates optimal
 // code. gcc is not happy when attempting to inline too deep.
 //
@@ skipping 2720 matching lines @@
     return GetHeap()->empty_fixed_array();
   } else if (has_external_array_elements()) {
     ExternalArray* empty_array = GetHeap()->EmptyExternalArrayForMap(this);
     ASSERT(!GetHeap()->InNewSpace(empty_array));
     return empty_array;
   } else if (has_fixed_typed_array_elements()) {
     FixedTypedArrayBase* empty_array =
       GetHeap()->EmptyFixedTypedArrayForMap(this);
     ASSERT(!GetHeap()->InNewSpace(empty_array));
     return empty_array;
+  } else if (has_dictionary_elements()) {
+    ASSERT(!GetHeap()->InNewSpace(GetHeap()->empty_slow_element_dictionary()));
+    return GetHeap()->empty_slow_element_dictionary();
   } else {
     UNREACHABLE();
   }
   return NULL;
 }
 
 
 Object** DescriptorArray::GetKeySlot(int descriptor_number) {
   ASSERT(descriptor_number < number_of_descriptors());
   return RawFieldOfElementAt(ToKeyIndex(descriptor_number));
@@ skipping 4234 matching lines @@
 #undef READ_SHORT_FIELD
 #undef WRITE_SHORT_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 #undef NOBARRIER_READ_BYTE_FIELD
 #undef NOBARRIER_WRITE_BYTE_FIELD
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_INL_H_