Add missing closed check to random access file.

runtime/bin/file_impl.dart

 // 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.
 
 class _FileInputStream extends _BaseDataInputStream implements InputStream {
   _FileInputStream(String name) {
     var file = new File(name);
     _data = [];
     _position = 0;
     var chained = file.open(FileMode.READ).chain((openedFile) {
@@ skipping 713 matching lines @@
       if (result != -1) {
         _id = result;
         return this;
       } else {
         throw new FileIOException("Cannot close file '$_name'");
       }
     });
   }
 
   void closeSync() {
+    _checkNotClosed();
     var id = _FileUtils.close(_id);
     if (id == -1) {
       throw new FileIOException("Cannot close file '$_name'");
     }
     _id = id;
   }
 
   Future<int> readByte() {
     _ensureFileService();
     Completer<int> completer = new Completer<int>();
@@ skipping 346 matching lines @@
           new FileIOException("File closed '$_name'"));
     });
     return completer.future;
   }
 
   final String _name;
   int _id;
 
   SendPort _fileService;
 }