Unify most of our utf8 implementations. This takes the implementation

lib/utf/utf.dart

Index: lib/utf/utf.dart
===================================================================
--- lib/utf/utf.dart	(revision 4552)
+++ lib/utf/utf.dart	(working copy)
@@ -2,36 +2,8 @@
 // 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);
-  }
-}
+#library("utf");
+#source("utf_core.dart");
+#source("utf8.dart");
+#source("utf16.dart");
+#source("utf32.dart");