Type check try statements

sdk/lib/io/file_impl.dart

 // Copyright (c) 2013, 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.
 
 part of dart.io;
 
 // Read the file in blocks of size 64k.
 const int _BLOCK_SIZE = 64 * 1024;
 
 
@@ skipping 516 matching lines @@
   List<String> readAsLinesSync({Encoding encoding: Encoding.UTF_8}) {
     return _decodeLines(readAsBytesSync(), encoding);
   }
 
   Future<File> writeAsBytes(List<int> bytes,
                             {FileMode mode: FileMode.WRITE}) {
     try {
       IOSink sink = openWrite(mode: mode);
       sink.add(bytes);
       sink.close();
-      return sink.done.then((_) => this);;
+      return sink.done.then((_) => this);
     } catch (e) {
       return new Future.error(e);
     }
   }
 
   void writeAsBytesSync(List<int> bytes, {FileMode mode: FileMode.WRITE}) {
     RandomAccessFile opened = openSync(mode: mode);
     opened.writeFromSync(bytes, 0, bytes.length);
     opened.closeSync();
   }
@@ skipping 448 matching lines @@
 
   Future _closedException() {
     return new Future.error(new FileIOException("File closed '$_path'"));
   }
 
   final String _path;
   int _id;
 
   SendPort _fileService;
 }