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

src/debug/debug.cc

Index: src/debug/debug.cc
diff --git a/src/debug/debug.cc b/src/debug/debug.cc
index 73af4cf7f71b390b7f0b46462417479273cb8dae..e54b7e9778d7c71b59141b2ad217954c96f517fd 100644
--- a/src/debug/debug.cc
+++ b/src/debug/debug.cc
@@ -2066,8 +2066,7 @@ void Debug::OnAsyncTaskEvent(debug::PromiseDebugActionType type, int id,
 void Debug::ProcessCompileEvent(v8::DebugEvent event, Handle<Script> script) {
   // Attach the correct debug id to the script. The debug id is used by the
   // inspector to filter scripts by native context.
-  FixedArray* array = isolate_->native_context()->embedder_data();
-  script->set_context_data(array->get(v8::Context::kDebugIdIndex));
+  script->set_context_data(isolate_->native_context()->debug_context_id());
   if (ignore_events()) return;
   if (!script->IsUserJavaScript() && script->type() != i::Script::TYPE_WASM) {
     return;