[api] Add a switch that controls if ES2015 tail call elimination feature is enabled or not.

include/v8-debug.h

 // Copyright 2008 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_V8_DEBUG_H_
 #define V8_V8_DEBUG_H_
 
 #include "v8.h"  // NOLINT(build/include)
 
 /**
@@ skipping 258 matching lines @@
    */
   static void SetLiveEditEnabled(Isolate* isolate, bool enable);
 
   /**
    * Returns array of internal properties specific to the value type. Result has
    * the following format: [<name>, <value>,...,<name>, <value>]. Result array
    * will be allocated in the current context.
    */
   static MaybeLocal<Array> GetInternalProperties(Isolate* isolate,
                                                  Local<Value> value);
+
+  /**
+   * Defines if the ES2015 tail call elimination feature is enabled or not.
+   * The change of this flag triggers deoptimization of all functions that
+   * contain calls at tail position.
+   */
+  static bool IsTailCallEliminationEnabled(Isolate* isolate);
+  static void SetTailCallEliminationEnabled(Isolate* isolate, bool enabled);
 };
 
 
 }  // namespace v8
 
 
 #undef EXPORT
 
 
 #endif  // V8_V8_DEBUG_H_