Recommit changing List.skip/take/revert returns Iterable and remove mappedBy.

tests/html/element_classes_test.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.
 
 library ElementTest;
 import '../../pkg/unittest/lib/unittest.dart';
 import '../../pkg/unittest/lib/html_config.dart';
 import 'dart:html';
 
 main() {
@@ skipping 48 matching lines @@
   });
 
   test('iterator', () {
     final classes = <String>[];
     for (var el in makeClassSet()) {
       classes.add(el);
     }
     expect(classes, unorderedEquals(['foo', 'bar', 'baz']));
   });
 
-  test('mappedBy', () {
+  test('map', () {
     expect(makeClassSet().map((c) => c.toUpperCase()).toList(),
         unorderedEquals(['FOO', 'BAR', 'BAZ']));
   });
 
   test('where', () {
     expect(makeClassSet().where((c) => c.contains('a')).toSet(),
         unorderedEquals(['bar', 'baz']));
   });
 
   test('every', () {
@@ skipping 79 matching lines @@
     expect(classes.intersection(['foo', 'qux', 'baz']),
         unorderedEquals(['foo', 'baz']));
   });
 
   test('clear', () {
     final classes = makeClassSet();
     classes.clear();
     expect(classes, equals([]));
   });
 }