Unify String.

corelib/src/implementation/string.dart

Index: corelib/src/implementation/string.dart
diff --git a/corelib/src/implementation/string.dart b/corelib/src/implementation/string.dart
new file mode 100644
index 0000000000000000000000000000000000000000..83f3d0de33477d27d76b93df25f9e2dd3709b349
--- /dev/null
+++ b/corelib/src/implementation/string.dart
@@ -0,0 +1,15 @@
+// Copyright (c) 2011, 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.
+
+class StringImplementation {
+  /**
+   * Factory implementation of String.fromCharCodes:
+   * Allocates a new String for the specified [charCodes].
+   */
+  factory String.fromCharCodes(List<int> charCodes) {
+    return _fromCharCodes(charCodes);
+  }
+
+  external static String _fromCharCodes(List<int> charCodes);
+}