Fix warnings and hints.

pkg/utf/lib/utf16.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 dart.utf;
+part of utf;
 
 /**
  * Decodes the UTF-16 bytes as an iterable. Thus, the consumer can only convert
  * as much of the input as needed. Determines the byte order from the BOM,
  * or uses big-endian as a default. This method always strips a leading BOM.
  * Set the [replacementCodepoint] to null to throw an ArgumentError
  * rather than replace the bad value. The default value for
  * [replacementCodepoint] is U+FFFD.
  */
 IterableUtf16Decoder decodeUtf16AsIterable(List<int> bytes, [int offset = 0,
@@ skipping 312 matching lines @@
   }
 
   int decode() {
     utf16EncodedBytesIterator.moveNext();
     int lo = utf16EncodedBytesIterator.current;
     utf16EncodedBytesIterator.moveNext();
     int hi = utf16EncodedBytesIterator.current;
     return (hi << 8) + lo;
   }
 }