Remove frog from the repository.

frog/lib/string_base.dart

-// 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 StringBase {
-  // TODO(jmesserly): this array copy is really unfortunate
-  // TODO(jmesserly): check the performance of String.fromCharCode.apply
-  // TODO(jmesserly): fix the generated JS name of factory ctors,
-  // they shouldn't be duplicating the name.
-  static String createFromCharCodes(List<int> charCodes) native @'''
-if (Object.getPrototypeOf(charCodes) !== Array.prototype) {
-  charCodes = new ListFactory.ListFactory$from$factory(charCodes);
-}
-return String.fromCharCode.apply(null, charCodes);
-''' {
-   // we may need to iterate over charCodes
-    var i = charCodes.iterator();  i.next(); i.hasNext();
-    new ListFactory.from(charCodes); // ensure List.from is generated
-  }
-
-  static String join(List<String> strings, String separator) {
-    if (strings.length == 0) return '';
-    String s = strings[0];
-    for (int i = 1; i < strings.length; i++) {
-      s = s + separator + strings[i];
-    }
-    return s;
-  }
-
-  static String concatAll(List<String> strings) => join(strings, "");
-}