Make V8 extras a separate type of native

src/snapshot/natives.h

 // Copyright 2011 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_SNAPSHOT_NATIVES_H_
 #define V8_SNAPSHOT_NATIVES_H_
 
 #include "src/vector.h"
 
 namespace v8 { class StartupData; }  // Forward declaration.
 
 namespace v8 {
 namespace internal {
 
-enum NativeType {
-  CORE, EXPERIMENTAL, D8, TEST
-};
+enum NativeType { CORE, EXPERIMENTAL, EXTRAS, D8, TEST };
 
 template <NativeType type>
 class NativesCollection {
  public:
   // Number of built-in scripts.
   static int GetBuiltinsCount();
   // Number of debugger implementation scripts.
   static int GetDebuggerCount();
 
   // These are used to access built-in scripts.  The debugger implementation
   // scripts have an index in the interval [0, GetDebuggerCount()).  The
   // non-debugger scripts have an index in the interval [GetDebuggerCount(),
   // GetNativesCount()).
   static int GetIndex(const char* name);
   static Vector<const char> GetScriptSource(int index);
   static Vector<const char> GetScriptName(int index);
   static Vector<const char> GetScriptsSource();
 };
 
 typedef NativesCollection<CORE> Natives;
 typedef NativesCollection<EXPERIMENTAL> ExperimentalNatives;
+typedef NativesCollection<EXTRAS> ExtraNatives;
 
 #ifdef V8_USE_EXTERNAL_STARTUP_DATA
 // Used for reading the natives at runtime. Implementation in natives-empty.cc
 void SetNativesFromFile(StartupData* natives_blob);
 void ReadNatives();
 void DisposeNatives();
 #endif
 
 } }  // namespace v8::internal
 
 #endif  // V8_SNAPSHOT_NATIVES_H_