Use symbols instead of hidden properties for i18n markers.

src/factory.h

 // Copyright 2014 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_FACTORY_H_
 #define V8_FACTORY_H_
 
 #include "src/isolate.h"
 
 namespace v8 {
@@ skipping 570 matching lines @@
 #undef STRUCT_MAP_ACCESSOR
 
 #define STRING_ACCESSOR(name, str)                              \
   inline Handle<String> name() {                                \
     return Handle<String>(bit_cast<String**>(                   \
         &isolate()->heap()->roots_[Heap::k##name##RootIndex])); \
   }
   INTERNALIZED_STRING_LIST(STRING_ACCESSOR)
 #undef STRING_ACCESSOR
 
+#define SYMBOL_ACCESSOR(name)                                   \
+  inline Handle<Symbol> name() {                                \
+    return Handle<Symbol>(bit_cast<Symbol**>(                   \
+        &isolate()->heap()->roots_[Heap::k##name##RootIndex])); \
+  }
+  PRIVATE_SYMBOL_LIST(SYMBOL_ACCESSOR)
+#undef SYMBOL_ACCESSOR
+
   inline void set_string_table(Handle<StringTable> table) {
     isolate()->heap()->set_string_table(*table);
   }
 
   Handle<String> hidden_string() {
     return Handle<String>(&isolate()->heap()->hidden_string_);
   }
 
   // Allocates a new SharedFunctionInfo object.
   Handle<SharedFunctionInfo> NewSharedFunctionInfo(
@@ skipping 99 matching lines @@
   // Reinitialize a JSProxy into an (empty) JS object of respective type and
   // size, but keeping the original prototype.  The receiver must have at least
   // the size of the new object.  The object is reinitialized and behaves as an
   // object that has been freshly allocated.
   void ReinitializeJSProxy(Handle<JSProxy> proxy, InstanceType type, int size);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_FACTORY_H_