Turn ZoneList inner_scopes into a linked list

src/debug/debug-scopes.cc

Index: src/debug/debug-scopes.cc
diff --git a/src/debug/debug-scopes.cc b/src/debug/debug-scopes.cc
index 9d21a293d202d7988f069884ee2f2cea23b0a40c..a68f9cc62477e7473b433a39f5d455587250eb04 100644
--- a/src/debug/debug-scopes.cc
+++ b/src/debug/debug-scopes.cc
@@ -799,8 +799,8 @@ void ScopeIterator::GetNestedScopeChain(Isolate* isolate, Scope* scope,
                                               scope->start_position(),
                                               scope->end_position()));
   }
-  for (int i = 0; i < scope->inner_scopes()->length(); i++) {
-    Scope* inner_scope = scope->inner_scopes()->at(i);
+  for (Scope* inner_scope = scope->inner_scope(); inner_scope != nullptr;
+       inner_scope = inner_scope->sibling()) {
     int beg_pos = inner_scope->start_position();
     int end_pos = inner_scope->end_position();
     DCHECK((beg_pos >= 0 && end_pos >= 0) || inner_scope->is_hidden());