Remove unused maps during marking garbage collections.

src/objects-inl.h

 // Copyright 2006-2008 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 539 matching lines @@
 #define WRITE_SHORT_FIELD(p, offset, value) \
   (*reinterpret_cast<uint16_t*>(FIELD_ADDR(p, offset)) = value)
 
 #define READ_BYTE_FIELD(p, offset) \
   (*reinterpret_cast<byte*>(FIELD_ADDR(p, offset)))
 
 #define WRITE_BYTE_FIELD(p, offset, value) \
   (*reinterpret_cast<byte*>(FIELD_ADDR(p, offset)) = value)
 
 
-Object* HeapObject::GetHeapObjectField(HeapObject* obj, int index) {
-  return READ_FIELD(obj, HeapObject::kHeaderSize + kPointerSize * index);
+Object** HeapObject::RawField(HeapObject* obj, int byte_offset) {
+  return &READ_FIELD(obj, byte_offset);
 }
 
 
 int Smi::value() {
   return reinterpret_cast<int>(this) >> kSmiTagSize;
 }
 
 
 Smi* Smi::FromInt(int value) {
   ASSERT(Smi::IsValid(value));
@@ skipping 1788 matching lines @@
 #undef WRITE_INT_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_