Track JS allocations as they arrive with no affection on performance when tracking is switched off

src/assembler.h

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // 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.
 //
@@ skipping 716 matching lines @@
       Isolate* isolate);
   static ExternalReference random_uint32_function(Isolate* isolate);
   static ExternalReference transcendental_cache_array_address(Isolate* isolate);
   static ExternalReference delete_handle_scope_extensions(Isolate* isolate);
 
   static ExternalReference get_date_field_function(Isolate* isolate);
   static ExternalReference date_cache_stamp(Isolate* isolate);
 
   static ExternalReference get_make_code_young_function(Isolate* isolate);
 
+  // New heap objects tracking support.
+  static ExternalReference is_tracking_allocations_address(Isolate* isolate);
+  static ExternalReference record_object_allocation_function(Isolate* isolate);
+
   // Deoptimization support.
   static ExternalReference new_deoptimizer_function(Isolate* isolate);
   static ExternalReference compute_output_frames_function(Isolate* isolate);
 
   // Log support.
   static ExternalReference log_enter_external_function(Isolate* isolate);
   static ExternalReference log_leave_external_function(Isolate* isolate);
 
   // Static data in the keyed lookup cache.
   static ExternalReference keyed_lookup_cache_keys(Isolate* isolate);
@@ skipping 327 matching lines @@
  public:
   NullCallWrapper() { }
   virtual ~NullCallWrapper() { }
   virtual void BeforeCall(int call_size) const { }
   virtual void AfterCall() const { }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_ASSEMBLER_H_