Added a simple dead code removal phase.

src/property-details.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 78 matching lines @@
   int pointer() { return DescriptorPointer::decode(value_); }
 
   PropertyDetails set_pointer(int i) { return PropertyDetails(value_, i); }
 
   // Conversion for storing details as Object*.
   explicit inline PropertyDetails(Smi* smi);
   inline Smi* AsSmi();
 
   PropertyType type() { return TypeField::decode(value_); }
 
-  PropertyAttributes attributes() { return AttributesField::decode(value_); }
+  PropertyAttributes attributes() const {
+    return AttributesField::decode(value_);
+  }
 
   int dictionary_index() {
     return DictionaryStorageField::decode(value_);
   }
 
   int descriptor_index() {
     return DescriptorStorageField::decode(value_);
   }
 
   inline PropertyDetails AsDeleted();
 
   static bool IsValidIndex(int index) {
     return DictionaryStorageField::is_valid(index);
   }
 
-  bool IsReadOnly() { return (attributes() & READ_ONLY) != 0; }
-  bool IsDontDelete() { return (attributes() & DONT_DELETE) != 0; }
-  bool IsDontEnum() { return (attributes() & DONT_ENUM) != 0; }
-  bool IsDeleted() { return DeletedField::decode(value_) != 0;}
+  bool IsReadOnly() const { return (attributes() & READ_ONLY) != 0; }
+  bool IsDontDelete() const { return (attributes() & DONT_DELETE) != 0; }
+  bool IsDontEnum() const { return (attributes() & DONT_ENUM) != 0; }
+  bool IsDeleted() const { return DeletedField::decode(value_) != 0;}
 
   // Bit fields in value_ (type, shift, size). Must be public so the
   // constants can be embedded in generated code.
   class TypeField:                public BitField<PropertyType,       0,  3> {};
   class AttributesField:          public BitField<PropertyAttributes, 3,  3> {};
   class DeletedField:             public BitField<uint32_t,           6,  1> {};
   class DictionaryStorageField:   public BitField<uint32_t,           7, 24> {};
   class DescriptorStorageField:   public BitField<uint32_t,           7, 11> {};
   class DescriptorPointer:        public BitField<uint32_t,          18, 11> {};
 
   static const int kInitialIndex = 1;
 
  private:
   PropertyDetails(int value, int pointer) {
       value_ = DescriptorPointer::update(value, pointer);
   }
 
   uint32_t value_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_PROPERTY_DETAILS_H_