Re-land rev. 12849 and 12868 (Heavy cleanup of the external pointer API + related fix).

src/objects.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 889 matching lines @@
  public:
   // Type testing.
   bool IsObject() { return true; }
 
 #define IS_TYPE_FUNCTION_DECL(type_)  inline bool Is##type_();
   OBJECT_TYPE_LIST(IS_TYPE_FUNCTION_DECL)
   HEAP_OBJECT_TYPE_LIST(IS_TYPE_FUNCTION_DECL)
 #undef IS_TYPE_FUNCTION_DECL
 
   inline bool IsFixedArrayBase();
+  inline bool IsExternal();
 
   // Returns true if this object is an instance of the specified
   // function template.
   inline bool IsInstanceOf(FunctionTemplateInfo* type);
 
   inline bool IsStruct();
 #define DECLARE_STRUCT_PREDICATE(NAME, Name, name) inline bool Is##Name();
   STRUCT_LIST(DECLARE_STRUCT_PREDICATE)
 #undef DECLARE_STRUCT_PREDICATE
 
@@ skipping 1524 matching lines @@
                                        Object* value);
 
   // Set operation on FixedArray without incremental write barrier. Can
   // only be used if the object is guaranteed to be white (whiteness witness
   // is present).
   static inline void NoIncrementalWriteBarrierSet(FixedArray* array,
                                                   int index,
                                                   Object* value);
 
  private:
+  STATIC_CHECK(kHeaderSize == Internals::kFixedArrayHeaderSize);
+
   DISALLOW_IMPLICIT_CONSTRUCTORS(FixedArray);
 };
 
 
 // FixedDoubleArray describes fixed-sized arrays with element type double.
 class FixedDoubleArray: public FixedArrayBase {
  public:
   // Setter and getter for elements.
   inline double get_scalar(int index);
   inline int64_t get_representation(int index);
@@ skipping 6569 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_