[Isolates] Avoid dereferencing Isolate::Current() to check oddball identities...

src/objects.h

 // Copyright 2006-2009 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 4738 matching lines @@
 
 // The Oddball describes objects null, undefined, true, and false.
 class Oddball: public HeapObject {
  public:
   // [to_string]: Cached to_string computed at startup.
   DECL_ACCESSORS(to_string, String)
 
   // [to_number]: Cached to_number computed at startup.
   DECL_ACCESSORS(to_number, Object)
 
+  inline byte kind();
+  inline void set_kind(byte kind);
+
   // Casting.
   static inline Oddball* cast(Object* obj);
 
   // Dispatched behavior.
   void OddballIterateBody(ObjectVisitor* v);
 #ifdef DEBUG
   void OddballVerify();
 #endif
 
   // Initialize the fields.
-  Object* Initialize(const char* to_string, Object* to_number);
+  Object* Initialize(const char* to_string, Object* to_number, byte kind);
 
   // Layout description.
   static const int kToStringOffset = HeapObject::kHeaderSize;
   static const int kToNumberOffset = kToStringOffset + kPointerSize;
-  static const int kSize = kToNumberOffset + kPointerSize;
+  static const int kKindOffset = kToNumberOffset + kPointerSize;
+  static const int kSize = kKindOffset + kPointerSize;
+
+  static const byte kFalse = 0;
+  static const byte kTrue = 1;
+  static const byte kNotBooleanMask = ~1;
+  static const byte kTheHole = 2;
+  static const byte kNull = 3;
+  static const byte kUndefined = 4;
+  static const byte kOther = 5;
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(Oddball);
 };
 
 
 class JSGlobalPropertyCell: public HeapObject {
  public:
   // [value]: value of the global property.
   DECL_ACCESSORS(value, Object)
@@ skipping 571 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_