Correctly implemented removeWhere and retainWhere for elements in dart:html.

tests/html/element_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_individual_config.dart';
 import 'dart:async';
 import 'dart:html';
 import 'dart:svg' as svg;
@@ skipping 482 matching lines @@
     test('sublist', () {
       var el = makeElementWithChildren();
       expect(el.children.sublist(1, 2), isElementList);
     });
 
     test('getRange', () {
       var el = makeElementWithChildren();
       expect(el.children.getRange(1, 2).length, 1);
     });
 
+    test('retainWhere', () {
+      var el = makeElementWithChildren();
+      expect(el.children.length, 3);
+      el.children.retainWhere((e) => true);
+      expect(el.children.length, 3);
+
+      el = makeElementWithChildren();
+      expect(el.children.length, 3);
+      el.children.retainWhere((e) => false);
+      expect(el.children.length, 0);
+
+      el = makeElementWithChildren();
+      expect(el.children.length, 3);
+      el.children.retainWhere((e) => e.localName == 'input');
+      expect(el.children.length, 1);
+
+      el = makeElementWithChildren();
+      expect(el.children.length, 3);
+      el.children.retainWhere((e) => e.localName == 'br');
+      expect(el.children.length, 1);
+    });
+
+    test('removeWhere', () {
+      var el = makeElementWithChildren();
+      expect(el.children.length, 3);
+      el.children.removeWhere((e) => true);
+      expect(el.children.length, 0);
+
+      el = makeElementWithChildren();
+      expect(el.children.length, 3);
+      el.children.removeWhere((e) => false);
+      expect(el.children.length, 3);
+
+      el = makeElementWithChildren();
+      expect(el.children.length, 3);
+      el.children.removeWhere((e) => e.localName == 'input');
+      expect(el.children.length, 2);
+
+      el = makeElementWithChildren();
+      expect(el.children.length, 3);
+      el.children.removeWhere((e) => e.localName == 'br');
+      expect(el.children.length, 2);
+    });
+
     testUnsupported('sort', () {
       var l = makeElementWithChildren().children;
       l.sort();
     });
 
     testUnsupported('setRange', () {
       var l = makeElementWithChildren().children;
       l.setRange(0, 0, []);
     });
 
@@ skipping 162 matching lines @@
     });
 
     test('sublist', () {
       var range = makeElList().sublist(1, 3);
       expect(range, isElementList);
       expect(range[0], isImageElement);
       expect(range[1], isInputElement);
     });
   });
 }