Allow hidden properties and implement GetIdentityHash

src/heap.h

 // Copyright 2006-2008 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 177 matching lines @@
   V(invalid_lhs_in_prefix_op_symbol, "invalid_lhs_in_prefix_op")         \
   V(illegal_return_symbol, "illegal_return")                             \
   V(illegal_break_symbol, "illegal_break")                               \
   V(illegal_continue_symbol, "illegal_continue")                         \
   V(unknown_label_symbol, "unknown_label")                               \
   V(redeclaration_symbol, "redeclaration")                               \
   V(failure_symbol, "<failure>")                                         \
   V(space_symbol, " ")                                                   \
   V(exec_symbol, "exec")                                                 \
   V(zero_symbol, "0")                                                    \
-  V(global_eval_symbol, "GlobalEval")
+  V(global_eval_symbol, "GlobalEval")                                    \
+  V(identity_hash_symbol, "v8::IdentityHash")
 
 
 // Forward declaration of the GCTracer class.
 class GCTracer;
 
 
 // The all static Heap captures the interface to the global object heap.
 // All JavaScript contexts by this process share the same object heap.
 
 class Heap : public AllStatic {
@@ skipping 430 matching lines @@
 
 // Utility type maps
 #define STRUCT_MAP_ACCESSOR(NAME, Name, name) \
     static Map* name##_map() { return name##_map_; }
   STRUCT_LIST(STRUCT_MAP_ACCESSOR)
 #undef STRUCT_MAP_ACCESSOR
 
 #define SYMBOL_ACCESSOR(name, str) static String* name() { return name##_; }
   SYMBOL_LIST(SYMBOL_ACCESSOR)
 #undef SYMBOL_ACCESSOR
+  
+  // The hidden_symbol is special because it is the empty string, but does
+  // not match the empty string.
+  static String* hidden_symbol() { return hidden_symbol_; }
 
   // Iterates over all roots in the heap.
   static void IterateRoots(ObjectVisitor* v);
   // Iterates over all strong roots in the heap.
   static void IterateStrongRoots(ObjectVisitor* v);
 
   // Iterates remembered set of an old space.
   static void IterateRSet(PagedSpace* space, ObjectSlotCallback callback);
 
   // Iterates a range of remembered set addresses starting with rset_start
@@ skipping 233 matching lines @@
 #undef ROOT_DECLARATION
 
 // Utility type maps
 #define DECLARE_STRUCT_MAP(NAME, Name, name) static Map* name##_map_;
   STRUCT_LIST(DECLARE_STRUCT_MAP)
 #undef DECLARE_STRUCT_MAP
 
 #define SYMBOL_DECLARATION(name, str) static String* name##_;
   SYMBOL_LIST(SYMBOL_DECLARATION)
 #undef SYMBOL_DECLARATION
+  
+  // The special hidden symbol which is an empty string, but does not match
+  // any string when looked up in properties.
+  static String* hidden_symbol_;
 
   // GC callback function, called before and after mark-compact GC.
   // Allocations in the callback function are disallowed.
   static GCCallback global_gc_prologue_callback_;
   static GCCallback global_gc_epilogue_callback_;
 
   // Checks whether a global GC is necessary
   static GarbageCollector SelectGarbageCollector(AllocationSpace space);
 
   // Performs garbage collection
@@ skipping 392 matching lines @@
   int marked_count_;
 
   // The count from the end of the previous full GC.  Will be zero if there
   // was no previous full GC.
   int previous_marked_count_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_HEAP_H_