Use the distinguished class, ApiFailure, to signal when a Dart_Result is

runtime/vm/raw_object_snapshot.cc

 // Copyright (c) 2011, 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.
 
 #include "vm/bigint_operations.h"
 #include "vm/object.h"
 #include "vm/object_store.h"
 #include "vm/snapshot.h"
 #include "vm/visitor.h"
 
@@ skipping 823 matching lines @@
 }
 
 
 void RawUnhandledException::WriteTo(SnapshotWriter* writer,
                                     intptr_t object_id,
                                     bool serialize_classes) {
   UNIMPLEMENTED();
 }
 
 
+RawApiFailure* ApiFailure::ReadFrom(SnapshotReader* reader,
+                                    intptr_t object_id,
+                                    bool classes_serialized) {
+  UNIMPLEMENTED();
+  return ApiFailure::null();
+}
+
+
+void RawApiFailure::WriteTo(SnapshotWriter* writer,
+                            intptr_t object_id,
+                            bool serialize_classes) {
+  UNIMPLEMENTED();
+}
+
+
 RawInstance* Instance::ReadFrom(SnapshotReader* reader,
                                 intptr_t object_id,
                                 bool classes_serialized) {
   UNREACHABLE();
   return Instance::null();
 }
 
 
 void RawInstance::WriteTo(SnapshotWriter* writer,
                           intptr_t object_id,
@@ skipping 466 matching lines @@
   // Write out all the other fields.
   writer->Write<RawObject*>(ptr()->num_bracket_expressions_);
   writer->WriteObject(ptr()->pattern_);
   writer->Write<intptr_t>(ptr()->type_);
   writer->Write<intptr_t>(ptr()->flags_);
 
   // Do not write out the data part which is native.
 }
 
 }  // namespace dart