Make V8 extras a separate type of native

src/heap/heap.cc

 // Copyright 2012 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/v8.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/base/bits.h"
 #include "src/base/once.h"
@@ skipping 3062 matching lines @@
   set_regexp_multiple_cache(*factory->NewFixedArray(
       RegExpResultsCache::kRegExpResultsCacheSize, TENURED));
 
   // Allocate cache for external strings pointing to native source code.
   set_natives_source_cache(
       *factory->NewFixedArray(Natives::GetBuiltinsCount()));
 
   set_experimental_natives_source_cache(
       *factory->NewFixedArray(ExperimentalNatives::GetBuiltinsCount()));
 
+  set_extra_natives_source_cache(
+      *factory->NewFixedArray(ExtraNatives::GetBuiltinsCount()));
+
   set_undefined_cell(*factory->NewCell(factory->undefined_value()));
 
   // The symbol registry is initialized lazily.
   set_symbol_registry(Smi::FromInt(0));
 
   // Allocate object to hold object observation state.
   set_observation_state(*factory->NewJSObjectFromMap(
       factory->NewMap(JS_OBJECT_TYPE, JSObject::kHeaderSize)));
 
   // Microtask queue uses the empty fixed array as a sentinel for "empty".
@@ skipping 3403 matching lines @@
       }
       delete list;
     } else {
       prev = list;
     }
     list = next;
   }
 }
 }
 }  // namespace v8::internal