Add map transition for observed objects

src/heap.cc

 // Copyright 2012 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 3154 matching lines @@
     if (!maybe_obj->ToObject(&obj)) return false;
   }
   set_frozen_symbol(Symbol::cast(obj));
 
   { MaybeObject* maybe_obj = SeededNumberDictionary::Allocate(this, 0, TENURED);
     if (!maybe_obj->ToObject(&obj)) return false;
   }
   SeededNumberDictionary::cast(obj)->set_requires_slow_elements();
   set_empty_slow_element_dictionary(SeededNumberDictionary::cast(obj));
 
+  { MaybeObject* maybe_obj = AllocateSymbol();
+    if (!maybe_obj->ToObject(&obj)) return false;
+  }
+  set_observed_symbol(Symbol::cast(obj));
+
   // Handling of script id generation is in Factory::NewScript.
   set_last_script_id(Smi::FromInt(v8::Script::kNoScriptId));
 
   // Initialize keyed lookup cache.
   isolate_->keyed_lookup_cache()->Clear();
 
   // Initialize context slot cache.
   isolate_->context_slot_cache()->Clear();
 
   // Initialize descriptor cache.
@@ skipping 4951 matching lines @@
   if (FLAG_parallel_recompilation) {
     heap_->relocation_mutex_->Lock();
 #ifdef DEBUG
     heap_->relocation_mutex_locked_by_optimizer_thread_ =
         heap_->isolate()->optimizing_compiler_thread()->IsOptimizerThread();
 #endif  // DEBUG
   }
 }
 
 } }  // namespace v8::internal