Cleanup in //runtime/bin

runtime/bin/io_natives.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 BIN_IO_NATIVES_H_
 #define BIN_IO_NATIVES_H_
 
 #include "include/dart_api.h"
 
-
 namespace dart {
 namespace bin {
 
 Dart_NativeFunction IONativeLookup(Dart_Handle name,
                                    int argument_count,
                                    bool* auto_setup_scope);
 
 const uint8_t* IONativeSymbol(Dart_NativeFunction nf);
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // BIN_IO_NATIVES_H_