[debug,api] Do not use embedder field for debug context id.

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 8280 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. */
   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 };

[jochen (gone - plz use gerrit), 2017/04/10 12:50:34]

this won't work unless you first clean up blink 

-
-  /**
    * 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.
+   * previous call to SetEmbedderData with the same index.
    */
   V8_INLINE Local<Value> GetEmbedderData(int index);
 
   /**
    * Gets the binding object used by V8 extras. Extra natives get a reference
    * to this object and can use it to "export" functionality by adding
    * properties. Extra natives can also "import" functionality by accessing
    * properties added by the embedder using the V8 API.
    */
   Local<Object> GetExtrasBindingObject();
@@ skipping 1679 matching lines @@
  */
 
 
 }  // namespace v8
 
 
 #undef TYPE_CHECK
 
 
 #endif  // INCLUDE_V8_H_