Modernize the package's style.

lib/src/comparators.dart

 // Copyright (c) 2015, 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 dart.pkg.collection.comparators;
-
 // Character constants.
 const int _zero         = 0x30;
 const int _upperCaseA   = 0x41;
 const int _upperCaseZ   = 0x5a;
 const int _lowerCaseA   = 0x61;
 const int _lowerCaseZ   = 0x7a;
 const int _asciiCaseBit = 0x20;
 
 /// Checks if strings [a] and [b] differ only on the case of ASCII letters.
 ///
@@ skipping 373 matching lines @@
 /// If there is no non-zero digits before, then leading zeros at [index]
 /// are also ignored when comparing numerically. If there is a non-zero digit
 /// before, then zeros at [index] are significant.
 bool _isNonZeroNumberSuffix(String string, int index) {
   while (--index >= 0) {
     int char = string.codeUnitAt(index);
     if (char != _zero) return _isDigit(char);
   }
   return false;
 }