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

src/d8.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 <errno.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/stat.h>
 
 #include <algorithm>
@@ skipping 620 matching lines @@
       : module_to_directory_map(10, ModuleGlobalHash(isolate)) {}
 
   // Map from normalized module specifier to Module.
   std::unordered_map<std::string, Global<Module>> specifier_to_module_map;
   // Map from Module to the directory that Module was loaded from.
   std::unordered_map<Global<Module>, std::string, ModuleGlobalHash>
       module_to_directory_map;
 };
 
 enum {
-  // The debugger reserves the first slot in the Context embedder data.
-  kDebugIdIndex = Context::kDebugIdIndex,
   kModuleEmbedderDataIndex,
   kInspectorClientIndex
 };
 
 void InitializeModuleEmbedderData(Local<Context> context) {
   context->SetAlignedPointerInEmbedderData(
       kModuleEmbedderDataIndex, new ModuleEmbedderData(context->GetIsolate()));
 }
 
 ModuleEmbedderData* GetModuleDataFromContext(Local<Context> context) {
@@ skipping 2398 matching lines @@
 }
 
 }  // namespace v8
 
 
 #ifndef GOOGLE3
 int main(int argc, char* argv[]) {
   return v8::Shell::Main(argc, argv);
 }
 #endif