Keep a trail while checking upper bounds in the VM in order to properly handle

runtime/vm/class_finalizer.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_CLASS_FINALIZER_H_
 #define VM_CLASS_FINALIZER_H_
 
 #include "vm/allocation.h"
 #include "vm/growable_array.h"
 #include "vm/object.h"
@@ skipping 133 matching lines @@
                                     PendingTypes* pending_types,
                                     TrailPtr trail);
   static void CheckRecursiveType(const Class& cls,
                                  const AbstractType& type,
                                  PendingTypes* pending_types);
   static void CheckTypeBounds(const Class& cls, const AbstractType& type);
   static void CheckTypeArgumentBounds(const Class& cls,
                                       const TypeArguments& arguments,
                                       Error* bound_error);
   static void ResolveUpperBounds(const Class& cls);
-  static void FinalizeUpperBounds(const Class& cls);
+  static void FinalizeUpperBounds(const Class& cls,
+                                  FinalizationKind finalization);
   static void ResolveSignature(const Class& cls, const Function& function);
   static void FinalizeSignature(const Class& cls, const Function& function);
   static void ResolveAndFinalizeMemberTypes(const Class& cls);
   static void PrintClassInformation(const Class& cls);
   static void CollectInterfaces(
       const Class& cls, GrowableArray<const Class*>* collected);
 
   static void MarkTypeMalformed(const Error& prev_error,
                                 const Script& script,
                                 const Type& type,
                                 const char* format,
                                 va_list args);
   static void ReportError(const Error& error);
   static void ReportError(const Class& cls,
                           TokenPosition token_pos,
                           const char* format, ...) PRINTF_ATTRIBUTE(3, 4);
   static void ReportErrors(const Error& prev_error,
                            const Class& cls,
                            TokenPosition token_pos,
                            const char* format, ...) PRINTF_ATTRIBUTE(4, 5);
 
   // Verify implicit offsets recorded in the VM for direct access to fields of
   // Dart instances (e.g: _TypedListView, _ByteDataView).
   static void VerifyImplicitFieldOffsets();
 };
 
 }  // namespace dart
 
 #endif  // VM_CLASS_FINALIZER_H_