[runtime] Replace hidden_string with a 0-hash-code private symbol

src/profiler/heap-snapshot-generator.cc

 // Copyright 2013 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.
 
 #include "src/profiler/heap-snapshot-generator.h"
 
 #include "src/code-stubs.h"
 #include "src/conversions.h"
 #include "src/debug/debug.h"
 #include "src/objects-body-descriptors.h"
@@ skipping 1580 matching lines @@
         case kField: {
           Representation r = details.representation();
           if (r.IsSmi() || r.IsDouble()) break;
 
           Name* k = descs->GetKey(i);
           FieldIndex field_index = FieldIndex::ForDescriptor(js_obj->map(), i);
           Object* value = js_obj->RawFastPropertyAt(field_index);
           int field_offset =
               field_index.is_inobject() ? field_index.offset() : -1;
 
-          if (k != heap_->hidden_string()) {
+          if (k != heap_->hidden_properties_symbol()) {
             SetDataOrAccessorPropertyReference(details.kind(), js_obj, entry, k,
                                                value, NULL, field_offset);
           } else {
             TagObject(value, "(hidden properties)");
             SetInternalReference(js_obj, entry, "hidden_properties", value,
                                  field_offset);
           }
           break;
         }
         case kDescriptor:
           SetDataOrAccessorPropertyReference(details.kind(), js_obj, entry,
                                              descs->GetKey(i),
                                              descs->GetValue(i));
           break;
       }
     }
   } else if (js_obj->IsJSGlobalObject()) {
     // We assume that global objects can only have slow properties.
     GlobalDictionary* dictionary = js_obj->global_dictionary();
     int length = dictionary->Capacity();
     for (int i = 0; i < length; ++i) {
       Object* k = dictionary->KeyAt(i);
       if (dictionary->IsKey(k)) {
         DCHECK(dictionary->ValueAt(i)->IsPropertyCell());
         PropertyCell* cell = PropertyCell::cast(dictionary->ValueAt(i));
         Object* value = cell->value();
-        if (k == heap_->hidden_string()) {
+        if (k == heap_->hidden_properties_symbol()) {
           TagObject(value, "(hidden properties)");
           SetInternalReference(js_obj, entry, "hidden_properties", value);
           continue;
         }
         PropertyDetails details = cell->property_details();
         SetDataOrAccessorPropertyReference(details.kind(), js_obj, entry,
                                            Name::cast(k), value);
       }
     }
   } else {
     NameDictionary* dictionary = js_obj->property_dictionary();
     int length = dictionary->Capacity();
     for (int i = 0; i < length; ++i) {
       Object* k = dictionary->KeyAt(i);
       if (dictionary->IsKey(k)) {
         Object* value = dictionary->ValueAt(i);
-        if (k == heap_->hidden_string()) {
+        if (k == heap_->hidden_properties_symbol()) {
           TagObject(value, "(hidden properties)");
           SetInternalReference(js_obj, entry, "hidden_properties", value);
           continue;
         }
         PropertyDetails details = dictionary->DetailsAt(i);
         SetDataOrAccessorPropertyReference(details.kind(), js_obj, entry,
                                            Name::cast(k), value);
       }
     }
   }
@@ skipping 1498 matching lines @@
   for (int i = 1; i < sorted_strings.length(); ++i) {
     writer_->AddCharacter(',');
     SerializeString(sorted_strings[i]);
     if (writer_->aborted()) return;
   }
 }
 
 
 }  // namespace internal
 }  // namespace v8