Use a private own symbol instead of a hidden property for hash codes

src/heap/heap.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_HEAP_HEAP_H_
 #define V8_HEAP_HEAP_H_
 
 #include <cmath>
 #include <map>
 
@@ skipping 253 matching lines @@
   V(undefined_string, "undefined")                             \
   V(value_of_string, "valueOf")                                \
   V(stack_string, "stack")                                     \
   V(toJSON_string, "toJSON")                                   \
   V(KeyedLoadMonomorphic_string, "KeyedLoadMonomorphic")       \
   V(KeyedStoreMonomorphic_string, "KeyedStoreMonomorphic")     \
   V(stack_overflow_string, "$stackOverflowBoilerplate")        \
   V(illegal_access_string, "illegal access")                   \
   V(cell_value_string, "%cell_value")                          \
   V(illegal_argument_string, "illegal argument")               \
-  V(identity_hash_string, "v8::IdentityHash")                  \
   V(closure_string, "(closure)")                               \
   V(dot_string, ".")                                           \
   V(compare_ic_string, "==")                                   \
   V(strict_compare_ic_string, "===")                           \
   V(infinity_string, "Infinity")                               \
   V(minus_infinity_string, "-Infinity")                        \
   V(query_colon_string, "(?:)")                                \
   V(Generator_string, "Generator")                             \
   V(throw_string, "throw")                                     \
   V(done_string, "done")                                       \
   V(value_string, "value")                                     \
   V(next_string, "next")                                       \
   V(byte_length_string, "byteLength")                          \
   V(byte_offset_string, "byteOffset")                          \
   V(minus_zero_string, "-0")                                   \
   V(Array_string, "Array")                                     \
   V(Error_string, "Error")                                     \
   V(RegExp_string, "RegExp")
 
 #define PRIVATE_SYMBOL_LIST(V)      \
   V(nonextensible_symbol)           \
   V(sealed_symbol)                  \
+  V(hash_code_symbol)               \
   V(frozen_symbol)                  \
   V(nonexistent_symbol)             \
   V(elements_transition_symbol)     \
   V(observed_symbol)                \
   V(uninitialized_symbol)           \
   V(megamorphic_symbol)             \
   V(premonomorphic_symbol)          \
   V(stack_trace_symbol)             \
   V(detailed_stack_trace_symbol)    \
   V(normal_ic_symbol)               \
@@ skipping 1415 matching lines @@
   };
 
   static const StringTypeTable string_type_table[];
   static const ConstantStringTable constant_string_table[];
   static const StructTable struct_table[];
 
   // The special hidden string which is an empty string, but does not match
   // any string when looked up in properties.
   String* hidden_string_;
 
+  void AddPrivateGlobalSymbols(Handle<Object> private_intern_table);
+
   // GC callback function, called before and after mark-compact GC.
   // Allocations in the callback function are disallowed.
   struct GCPrologueCallbackPair {
     GCPrologueCallbackPair(v8::Isolate::GCPrologueCallback callback,
                            GCType gc_type, bool pass_isolate)
         : callback(callback), gc_type(gc_type), pass_isolate_(pass_isolate) {}
     bool operator==(const GCPrologueCallbackPair& pair) const {
       return pair.callback == callback;
     }
     v8::Isolate::GCPrologueCallback callback;
@@ skipping 907 matching lines @@
   DisallowHeapAllocation no_allocation;  // i.e. no gc allowed.
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(PathTracer);
 };
 #endif  // DEBUG
 }
 }  // namespace v8::internal
 
 #endif  // V8_HEAP_HEAP_H_