- Change "static final" to "static const" in the lib/ directory.

lib/utf/utf8.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.
 
-final int _UTF8_ONE_BYTE_MAX = 0x7f;
-final int _UTF8_TWO_BYTE_MAX = 0x7ff;
-final int _UTF8_THREE_BYTE_MAX = 0xffff;
+const int _UTF8_ONE_BYTE_MAX = 0x7f;
+const int _UTF8_TWO_BYTE_MAX = 0x7ff;
+const int _UTF8_THREE_BYTE_MAX = 0xffff;
 
-final int _UTF8_LO_SIX_BIT_MASK = 0x3f;
+const int _UTF8_LO_SIX_BIT_MASK = 0x3f;
 
-final int _UTF8_FIRST_BYTE_OF_TWO_BASE = 0xc0;
-final int _UTF8_FIRST_BYTE_OF_THREE_BASE = 0xe0;
-final int _UTF8_FIRST_BYTE_OF_FOUR_BASE = 0xf0;
-final int _UTF8_FIRST_BYTE_OF_FIVE_BASE = 0xf8;
-final int _UTF8_FIRST_BYTE_OF_SIX_BASE = 0xfc;
+const int _UTF8_FIRST_BYTE_OF_TWO_BASE = 0xc0;
+const int _UTF8_FIRST_BYTE_OF_THREE_BASE = 0xe0;
+const int _UTF8_FIRST_BYTE_OF_FOUR_BASE = 0xf0;
+const int _UTF8_FIRST_BYTE_OF_FIVE_BASE = 0xf8;
+const int _UTF8_FIRST_BYTE_OF_SIX_BASE = 0xfc;
 
-final int _UTF8_FIRST_BYTE_OF_TWO_MASK = 0x1f;
-final int _UTF8_FIRST_BYTE_OF_THREE_MASK = 0xf;
-final int _UTF8_FIRST_BYTE_OF_FOUR_MASK = 0x7;
+const int _UTF8_FIRST_BYTE_OF_TWO_MASK = 0x1f;
+const int _UTF8_FIRST_BYTE_OF_THREE_MASK = 0xf;
+const int _UTF8_FIRST_BYTE_OF_FOUR_MASK = 0x7;
 
-final int _UTF8_FIRST_BYTE_BOUND_EXCL = 0xfe;
-final int _UTF8_SUBSEQUENT_BYTE_BASE = 0x80;
+const int _UTF8_FIRST_BYTE_BOUND_EXCL = 0xfe;
+const int _UTF8_SUBSEQUENT_BYTE_BASE = 0x80;
 
 /**
  * Decodes the UTF-8 bytes as an iterable. Thus, the consumer can only convert
  * as much of the input as needed. Set the replacementCharacter to null to
  * throw an IllegalArgumentException rather than replace the bad value.
  */
 IterableUtf8Decoder decodeUtf8AsIterable(List<int> bytes, [int offset = 0,
     int length,
     int replacementCodepoint = UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]) {
   return new IterableUtf8Decoder(bytes, offset, length, replacementCodepoint);
@@ skipping 219 matching lines @@
     if (validSequence && nonOverlong && inRange) {
       return value;
     } else if (replacementCodepoint != null) {
       return replacementCodepoint;
     } else {
       throw new IllegalArgumentException(
           "Invalid UTF8 at ${utf8EncodedBytesIterator.position - j}");
     }
   }
 }