Make base64 decoding return a Uint8List.

lib/src/base64.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.
 
 part of crypto;
 
 const Base64Codec BASE64 = const Base64Codec();
 
 const List<int> _decodeTable =
       const [ -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -1, -2, -2, -1, -2, -2,
@@ skipping 260 matching lines @@
 class Base64Decoder extends Converter<String, List<int>> {
 
   /**
    * Instantiates a new [Base64Decoder]
    */
   const Base64Decoder();
 
   List<int> convert(String input) {
     int length = input.length;
     if (length == 0) {
-      return new List<int>(0);
+      return new Uint8List<int>(0);
     }
 
     int normalLength = 0;
     int i = 0;
     // Count '\r', '\n' and illegal characters, check if
     // '/', '+' / '-', '_' are used consistently, for illegal characters,
     // throw an exception.
 
     while (i < length) {
       int codeUnit = input.codeUnitAt(i);
@@ skipping 30 matching lines @@
         padLength++;
         i -= 2;
       } else if (_decodeTable[currentCodeUnit] > 0) {
         break;
       } else if (currentCodeUnit == _PAD_BYTES[0]) {
         padLength++;
       }
       i--;
     }
     int outputLength = ((normalLength * 6) >> 3) - padLength;
-    List<int> out = new List<int>(outputLength);
+    List<int> out = new Uint8List<int>(outputLength);
 
     for (int i = 0, o = 0; o < outputLength; ) {
       // Accumulate 4 valid 6 bit Base 64 characters into an int.
       int x = 0;
       for (int j = 4; j > 0; ) {
         int c = _decodeTable[input.codeUnitAt(i++)];
         if (c >= 0) {
           x = ((x << 6) & 0x00FFFFFF) | c;
           j--;
         }
@@ skipping 47 matching lines @@
 
   void close() {
     if (_unconverted.isNotEmpty) {
       _outSink.add(_decoder.convert(_unconverted));
     }
     _outSink.close();
   }
 }