Unify most of our utf8 implementations. This takes the implementation

lib/utf/unicode.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.
-
-#library("unicode");
-#import("unicode_core.dart");
-
-/**
- * Provide a list of Unicode codepoints for a given string.
- */
-List<int> stringToCodepoints(String str) {
-  List<int> codepoints;
-  // TODO is16BitCodeUnit() is used to work around a bug with frog/dartc
-  // (http://code.google.com/p/dart/issues/detail?id=1357). Consider
-  // removing after this issue is resolved.
-  if (is16BitCodeUnit()) {
-    codepoints = utf16CodeUnitsToCodepoints(str.charCodes());
-  } else {
-    codepoints = str.charCodes();
-  }
-  return codepoints;
-}
-
-/**
- * Generate a string from the provided Unicode codepoints.
- */
-String codepointsToString(List<int> codepoints) {
-  // TODO is16BitCodeUnit() is used to work around a bug with frog/dartc
-  // (http://code.google.com/p/dart/issues/detail?id=1357). Consider
-  // removing after this issue is resolved.
-  if (is16BitCodeUnit()) {
-    return new String.fromCharCodes(
-        codepointsToUtf16CodeUnits(codepoints));
-  } else {
-    return new String.fromCharCodes(codepoints);
-  }
-}