[Intl] Cleanup some code

pkg/intl/tool/generate_locale_data_files.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.
 
 /**
  * A utility program to take locale data represented as a Dart map whose keys
  * are locale names and write it into individual JSON files named by locale.
  * This should be run any time the locale data changes.
  *
  * The files are written under "data/dates", in two subdirectories, "symbols"
@@ skipping 51 matching lines @@
 
 void writeSymbols(locale, symbols) {
   var file = new File(path.join(dataDirectory, 'symbols', '${locale}.json'));
   var output = file.openWrite();
   writeToJSON(symbols, output);
   output.close();
 }
 
 void writePatterns(locale, patterns) {
   var file = new File(path.join(dataDirectory, 'patterns', '${locale}.json'));
-  var output = file.openWrite();
-  output.write(JSON.encode(patterns));
-  output.close();
+  file.openWrite()..write(JSON.encode(patterns))..close();
 }
 
 void writeToJSON(dynamic data, IOSink out) {
   out.write(JSON.encode(data.serializeToMap()));
 }