[debugger] correctly find inner function scope.

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 <memory>
 
 #include "src/ast/ast.h"
 #include "src/ast/scopes.h"
@@ skipping 820 matching lines @@
         Object::GetPropertyOrElement(extension, key).ToHandleChecked();
     JSObject::SetOwnPropertyIgnoreAttributes(scope_object, key, value, NONE)
         .Check();
   }
 }
 
 void ScopeIterator::GetNestedScopeChain(Isolate* isolate, Scope* scope,
                                         int position) {
   if (scope->is_function_scope()) {
     // Do not collect scopes of nested inner functions inside the current one.
+    // Nested arrow functions could have the same end positions.
     Handle<JSFunction> function = frame_inspector_->GetFunction();
-    if (scope->end_position() < function->shared()->end_position()) return;
+    if (scope->start_position() > function->shared()->start_position() &&
+        scope->end_position() <= function->shared()->end_position()) {
+      return;
+    }
   }
   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->scope_info()));
   } else {
     nested_scope_chain_.Add(ExtendedScopeInfo(
         scope->scope_info(), scope->start_position(), scope->end_position()));
   }
   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