[es6] silence access-check failure for well-known symbol properties

src/objects.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include <iosfwd>
 
 #include "src/allocation.h"
@@ skipping 8394 matching lines @@
  public:
   // [name]: The print name of a symbol, or undefined if none.
   DECL_ACCESSORS(name, Object)
 
   DECL_INT_ACCESSORS(flags)
 
   // [is_private]: Whether this is a private symbol.  Private symbols can only
   // be used to designate own properties of objects.
   DECL_BOOLEAN_ACCESSORS(is_private)
 
+  // [is_well_known_symbol]: Whether this is a spec-defined well-known symbol,
+  // or not. Well-known symbols do not throw when an access check fails during
+  // a load.
+  DECL_BOOLEAN_ACCESSORS(is_well_known_symbol)
+
   DECLARE_CAST(Symbol)
 
   // Dispatched behavior.
   DECLARE_PRINTER(Symbol)
   DECLARE_VERIFIER(Symbol)
 
   // Layout description.
   static const int kNameOffset = Name::kSize;
   static const int kFlagsOffset = kNameOffset + kPointerSize;
   static const int kSize = kFlagsOffset + kPointerSize;
 
   typedef FixedBodyDescriptor<kNameOffset, kFlagsOffset, kSize> BodyDescriptor;
 
   void SymbolShortPrint(std::ostream& os);
 
  private:
   static const int kPrivateBit = 0;
+  static const int kWellKnownSymbolBit = 1;
 
   const char* PrivateSymbolToName() const;
 
 #if TRACE_MAPS
   friend class Name;  // For PrivateSymbolToName.
 #endif
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(Symbol);
 };
 
@@ skipping 2222 matching lines @@
   Handle<FixedArray> keys_;
   Handle<OrderedHashSet> set_;
   int length_;
   DISALLOW_COPY_AND_ASSIGN(KeyAccumulator);
 };
 
 }  // NOLINT, false-positive due to second-order macros.
 }  // NOLINT, false-positive due to second-order macros.
 
 #endif  // V8_OBJECTS_H_