introduce eternal handles

src/isolate.h

Index: src/isolate.h
diff --git a/src/isolate.h b/src/isolate.h
index 894d25d6f0e4ebdabb44a0bd15ee2dcd1e5888b0..97291ce5c54cb3fa9e5939166ae1691a3f04f2ff 100644
--- a/src/isolate.h
+++ b/src/isolate.h
@@ -922,6 +922,8 @@ class Isolate {
 
   GlobalHandles* global_handles() { return global_handles_; }
 
+  EternalHandles* eternal_handles() { return eternal_handles_; }
+
   ThreadManager* thread_manager() { return thread_manager_; }
 
   ContextSwitcher* context_switcher() { return context_switcher_; }
@@ -1288,6 +1290,7 @@ class Isolate {
   InnerPointerToCodeCache* inner_pointer_to_code_cache_;
   ConsStringIteratorOp* write_iterator_;
   GlobalHandles* global_handles_;
+  EternalHandles* eternal_handles_;
   ContextSwitcher* context_switcher_;
   ThreadManager* thread_manager_;
   RuntimeState runtime_state_;