Implementing weak referencing elements transition maps.

src/objects-inl.h

 // 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 1940 matching lines @@
     Map* transition_map, WriteBarrierMode mode) {
   ASSERT(this->length() > kTransitionsIndex);
   Heap* heap = GetHeap();
   WRITE_FIELD(this, kTransitionsOffset, transition_map);
   CONDITIONAL_WRITE_BARRIER(
       heap, this, kTransitionsOffset, transition_map, mode);
   ASSERT(DescriptorArray::cast(this));
 }
 
 
+void DescriptorArray::ClearElementsTransition() {
+  WRITE_FIELD(this, kTransitionsOffset, Smi::FromInt(0));
+}
+
+
 Object** DescriptorArray::GetKeySlot(int descriptor_number) {
   ASSERT(descriptor_number < number_of_descriptors());
   return HeapObject::RawField(
       reinterpret_cast<HeapObject*>(this),
       OffsetOfElementAt(ToKeyIndex(descriptor_number)));
 }
 
 
 String* DescriptorArray::GetKey(int descriptor_number) {
   ASSERT(descriptor_number < number_of_descriptors());
@@ skipping 3206 matching lines @@
 #undef WRITE_UINT32_FIELD
 #undef READ_SHORT_FIELD
 #undef WRITE_SHORT_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_INL_H_