Get rid of all the library tags.

lib/src/utils.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 crypto.utils;
-
 /// A bitmask that limits an integer to 32 bits.
 const mask32 = 0xFFFFFFFF;
 
 /// The highest value representable by a 64-bit unsigned integer.
 const maxUint64 = 0xFFFFFFFFFFFFFFFF;
 
 /// The number of bits in a byte.
 const bitsPerByte = 8;
 
 /// The number of bytes in a 32-bit word.
 const bytesPerWord = 4;
 
 /// Adds [x] and [y] with 32-bit overflow semantics.
 int add32(int x, int y) => (x + y) & mask32;
 
 /// Bitwise rotates [val] to the left by [shift], obeying 32-bit overflow
 /// semantics.
 int rotl32(int val, int shift) {
   var modShift = shift & 31;
   return ((val << modShift) & mask32) |
       ((val & mask32) >> (32 - modShift));
 }