Add some support for the code-point code-unit distinction.

sdk/lib/utf/utf_core.dart

Index: sdk/lib/utf/utf_core.dart
diff --git a/sdk/lib/utf/utf_core.dart b/sdk/lib/utf/utf_core.dart
index a1cedcece985c193b05a446ef78147a3bfc7d212..f22290bf23e3b7c8f19c25dbd746b2f5575bcdce 100644
--- a/sdk/lib/utf/utf_core.dart
+++ b/sdk/lib/utf/utf_core.dart
@@ -2,48 +2,6 @@
 // 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.
 
-// TODO(jmesserly): would be nice to have this on String (dartbug.com/6501).
-/**
- * Provide a list of Unicode codepoints for a given string.
- */
-List<int> stringToCodepoints(String str) {
-  // Note: str.charCodes gives us 16-bit code units on all Dart implementations.
-  // So we need to convert. The same is not true of "new String.fromCharCodes",
-  // which accepts code points on the VM but not dart2js (dartbug.com/1357).
-  return _utf16CodeUnitsToCodepoints(str.charCodes);
-}
-
-/**
- * Generate a string from the provided Unicode codepoints.
- */
-String codepointsToString(List<int> codepoints) {
-  // TODO _is16BitCodeUnit() is used to work around a bug with dart2js
-  // (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);
-  }
-}
-
-/*
- * Test for presence of bug related to the use of UTF-16 code units for
- * Dart compiled to JS.
- */
-bool _test16BitCodeUnit = null;
-// TODO _is16BitCodeUnit() is used to work around a bug with dart2js
-// (http://code.google.com/p/dart/issues/detail?id=1357). Consider
-// removing after this issue is resolved.
-bool _is16BitCodeUnit() {
-  if (_test16BitCodeUnit == null) {
-    _test16BitCodeUnit = (new String.fromCharCodes([0x1D11E])) ==
-        (new String.fromCharCodes([0xD11E]));
-  }
-  return _test16BitCodeUnit;
-}
-
 /**
  * Invalid codepoints or encodings may be substituted with the value U+fffd.
  */