Auto create ApiLocalScope before calling native functions, this ensures that

runtime/bin/builtin_natives.cc

 // 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.
 
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
 
 #include "include/dart_api.h"
 
@@ skipping 79 matching lines @@
       return reinterpret_cast<Dart_NativeFunction>(entry->function_);
     }
   }
   return IONativeLookup(name, argument_count);
 }
 
 
 // Implementation of native functions which are used for some
 // test/debug functionality in standalone dart mode.
 void FUNCTION_NAME(Logger_PrintString)(Dart_NativeArguments args) {
-  Dart_EnterScope();
   intptr_t length = 0;
   uint8_t* chars = NULL;
   Dart_Handle str = Dart_GetNativeArgument(args, 0);
   Dart_Handle result = Dart_StringToUTF8(str, &chars, &length);
   if (Dart_IsError(result)) {
     // TODO(turnidge): Consider propagating some errors here.  What if
     // an isolate gets interrupted by the embedder in the middle of
     // Dart_StringToUTF8?  We need to make sure not to swallow the
     // interrupt.
     fputs(Dart_GetError(result), stdout);
   } else {
     fwrite(chars, sizeof(*chars), length, stdout);
   }
   fputc('\n', stdout);
   fflush(stdout);
-  Dart_ExitScope();
 }
 
 }  // namespace bin
 }  // namespace dart