Add support for API accessors that prohibit overwriting by accessors...

src/objects.h

Index: src/objects.h
===================================================================
--- src/objects.h	(revision 654)
+++ src/objects.h	(working copy)
@@ -1280,6 +1280,7 @@
   void LookupRealNamedProperty(String* name, LookupResult* result);
   void LookupRealNamedPropertyInPrototypes(String* name, LookupResult* result);
   void LookupCallbackSetterInPrototypes(String* name, LookupResult* result);
+  void LookupCallback(String* name, LookupResult* result);
 
   // Returns the number of properties on this object filtering out properties
   // with the specified attributes (ignoring interceptors).
@@ -2364,14 +2365,9 @@
 
   // Tells whether the instance needs security checks when accessing its
   // properties.
-  inline void set_is_access_check_needed() {
-    set_bit_field(bit_field() | (1 << kIsAccessCheckNeeded));
-  }
+  inline void set_is_access_check_needed(bool access_check_needed);
+  inline bool is_access_check_needed();
 
-  inline bool is_access_check_needed() {
-    return ((1 << kIsAccessCheckNeeded) & bit_field()) != 0;
-  }
-
   // [prototype]: implicit prototype object.
   DECL_ACCESSORS(prototype, Object)
 
@@ -3717,6 +3713,9 @@
   inline bool all_can_write();
   inline void set_all_can_write(bool value);
 
+  inline bool prohibits_overwriting();
+  inline void set_prohibits_overwriting(bool value);
+
   inline PropertyAttributes property_attributes();
   inline void set_property_attributes(PropertyAttributes attributes);
 
@@ -3736,9 +3735,10 @@
 
  private:
   // Bit positions in flag.
-  static const int kAllCanReadBit  = 0;
+  static const int kAllCanReadBit = 0;
   static const int kAllCanWriteBit = 1;
-  class AttributesField: public BitField<PropertyAttributes, 2, 3> {};
+  static const int kProhibitsOverwritingBit = 2;
+  class AttributesField: public BitField<PropertyAttributes, 3, 3> {};
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(AccessorInfo);
 };