Clean up mime package.

pkg/mime/lib/src/magic_number.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.
 
 library mime.magic_number;
 
 class MagicNumber {
   final String mimeType;
   final List<int> numbers;
   final List<int> mask;
 
   const MagicNumber(this.mimeType, this.numbers, {this.mask});
 
   bool matches(List<int> header) {
     if (header.length < numbers.length) return false;
 
     for (int i = 0; i < numbers.length; i++) {
       if (mask != null) {
         if ((mask[i] & numbers[i]) != (mask[i] & header[i])) return false;
       } else {
         if (numbers[i] != header[i]) return false;
       }
     }
 
     return true;
   }
 
 }
 
+const int DEFAULT_MAGIC_NUMBERS_MAX_LENGTH = 12;
+
 const List<MagicNumber> DEFAULT_MAGIC_NUMBERS = const [
   const MagicNumber('application/pdf', const [0x25, 0x50, 0x44, 0x46]),
   const MagicNumber('application/postscript', const [0x25, 0x51]),
   const MagicNumber('image/gif', const [0x47, 0x49, 0x46, 0x38, 0x37, 0x61]),
   const MagicNumber('image/gif', const [0x47, 0x49, 0x46, 0x38, 0x39, 0x61]),
   const MagicNumber('image/jpeg', const [0xFF, 0xD8]),
   const MagicNumber('image/png',
       const [0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A]),
   const MagicNumber('image/tiff', const [0x49, 0x49, 0x2A, 0x00]),
   const MagicNumber('image/tiff', const [0x4D, 0x4D, 0x00, 0x2A]),
   const MagicNumber(
       'video/mp4',
       const [0x00, 0x00, 0x00, 0x00, 0x66, 0x74,
              0x79, 0x70, 0x33, 0x67, 0x70, 0x35],
       mask: const [0xFF, 0xFF, 0xFF, 0x00, 0xFF, 0xFF,
                    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF])
 ];