Introduce explicit constant for per Context debug data set by embedder

include/v8.h

 // 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.
 
 /** \mainpage V8 API Reference Guide
  *
  * V8 is Google's open source JavaScript engine.
  *
  * This set of documents provides reference material generated from the
  * V8 header file, include/v8.h.
@@ skipping 6237 matching lines @@
   /**
    * Exit this context.  Exiting the current context restores the
    * context that was in place when entering the current context.
    */
   void Exit();
 
   /** Returns an isolate associated with a current context. */
   v8::Isolate* GetIsolate();
 
   /**
+   * The field at kDebugIdIndex is reserved for V8 debugger implementation.
+   * The value is propagated to the scripts compiled in given Context and
+   * can be used for filtering scripts.
+   */
+  enum EmbedderDataFields { kDebugIdIndex = 0 };
+
+  /**
    * Gets the embedder data with the given index, which must have been set by a
    * previous call to SetEmbedderData with the same index. Note that index 0
    * currently has a special meaning for Chrome's debugger.
    */
   V8_INLINE Local<Value> GetEmbedderData(int index);
 
   /**
    * Sets the embedder data with the given index, growing the data as
    * needed. Note that index 0 currently has a special meaning for Chrome's
    * debugger.
@@ skipping 1648 matching lines @@
  */
 
 
 }  // namespace v8
 
 
 #undef TYPE_CHECK
 
 
 #endif  // V8_H_