Turn ZoneList inner_scopes into a linked list

src/debug/debug-scopes.cc

 // Copyright 2015 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 "src/debug/debug-scopes.h"
 
 #include "src/ast/scopes.h"
 #include "src/compiler.h"
 #include "src/debug/debug.h"
 #include "src/frames-inl.h"
@@ skipping 781 matching lines @@
                                         int position) {
   if (scope->is_hidden()) {
     // We need to add this chain element in case the scope has a context
     // associated. We need to keep the scope chain and context chain in sync.
     nested_scope_chain_.Add(ExtendedScopeInfo(scope->GetScopeInfo(isolate)));
   } else {
     nested_scope_chain_.Add(ExtendedScopeInfo(scope->GetScopeInfo(isolate),
                                               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());
     if (beg_pos <= position && position < end_pos) {
       GetNestedScopeChain(isolate, inner_scope, position);
       return;
     }
   }
 }
 
 }  // namespace internal
 }  // namespace v8