Add ES5 Object.isExtensible and Object.preventExtensions.

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 1498 matching lines @@
   // Note: this call does not update write barrier, it is caller's
   // reponsibility to ensure that *v* can be collected without WB here.
   inline void InitializeBody(int object_size);
 
   // Check whether this object references another object
   bool ReferencesObject(Object* obj);
 
   // Casting.
   static inline JSObject* cast(Object* obj);
 
+  // Disalow further properties to be added to the object.
+  Object* PreventExtensions();
+
+
   // Dispatched behavior.
   void JSObjectIterateBody(int object_size, ObjectVisitor* v);
   void JSObjectShortPrint(StringStream* accumulator);
 #ifdef DEBUG
   void JSObjectPrint();
   void JSObjectVerify();
   void PrintProperties();
   void PrintElements();
 
   // Structure for collecting spill information about JSObjects.
@@ skipping 1444 matching lines @@
 
   // Tells whether the instance has a call-as-function handler.
   inline void set_has_instance_call_handler() {
     set_bit_field(bit_field() | (1 << kHasInstanceCallHandler));
   }
 
   inline bool has_instance_call_handler() {
     return ((1 << kHasInstanceCallHandler) & bit_field()) != 0;
   }
 
-  inline void set_is_extensible() {
-    set_bit_field2(bit_field2() | (1 << kIsExtensible));
-  }
-
-  inline bool is_extensible() {
-    return ((1 << kIsExtensible) & bit_field2()) != 0;
-  }
+  inline void set_is_extensible(bool value);
+  inline bool is_extensible();
 
   // Tells whether the instance has fast elements.
   void set_has_fast_elements(bool value) {
     if (value) {
       set_bit_field2(bit_field2() | (1 << kHasFastElements));
     } else {
       set_bit_field2(bit_field2() & ~(1 << kHasFastElements));
     }
   }
 
@@ skipping 2334 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_