Use the return value of vm native methods to set the return value,

vm/bootstrap.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/bootstrap.h"
 
 #include "include/dart_api.h"
 
+#include "vm/bootstrap_natives.h"
 #include "vm/compiler.h"
 #include "vm/dart_api_impl.h"
 #include "vm/object.h"
 #include "vm/object_store.h"
 
 namespace dart {
 
 DEFINE_FLAG(bool, print_bootstrap, false, "Print the bootstrap source.");
 
 
@@ skipping 53 matching lines @@
   const Error& error = Error::Handle(Compiler::Compile(library, script));
   if (error.IsNull()) {
     library.SetLoaded();
   } else {
     library.SetLoadError();
   }
   return error.raw();
 }
 
 }  // namespace dart