| Index: src/isolate.h | 
| diff --git a/src/isolate.h b/src/isolate.h | 
| index 5abbc75df9f882e7b6af299c9bacbb6aa1c6ea0c..de72475e95277ded022663202739c4c6e6301e22 100644 | 
| --- a/src/isolate.h | 
| +++ b/src/isolate.h | 
| @@ -387,6 +387,7 @@ typedef List<HeapObject*> DebugObjectCache; | 
| V(uint32_t, per_isolate_assert_data, 0xFFFFFFFFu)                            \ | 
| V(PromiseRejectCallback, promise_reject_callback, NULL)                      \ | 
| V(const v8::StartupData*, snapshot_blob, NULL)                               \ | 
| +  V(JavascriptExecutionObserver*, execution_observer, NULL)                    \ | 
| ISOLATE_INIT_SIMULATOR_LIST(V) | 
|  | 
| #define THREAD_LOCAL_TOP_ACCESSOR(type, name)                        \ | 
|  |