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

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 95e0ae5403d6a0279d0b55fd1c1b9c0ca13f7251..6381c3c48313587e314ea0986af351c13c9d8135 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -8412,6 +8412,11 @@ class Symbol: public Name {
   // 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.
@@ -8429,6 +8434,7 @@ class Symbol: public Name {
 
  private:
   static const int kPrivateBit = 0;
+  static const int kWellKnownSymbolBit = 1;
 
   const char* PrivateSymbolToName() const;