Make 'where' lazy.

tests/html/queryall_test.dart

 // Copyright (c) 2012, 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 NodeListTest;
 import '../../pkg/unittest/lib/unittest.dart';
 import '../../pkg/unittest/lib/html_config.dart';
 import 'dart:html';
 
 main() {
@@ skipping 41 matching lines @@
       expect(all.length, equals(2));
     });
 
   test('queryAll-contains', () {
       List<Element> all = queryAll('*');
       for (var e in all) {
         expect(all.contains(e), isTrue);
       }
     });
 
-  test('queryAll-filter', () {
+  test('queryAll-where', () {
       List<Element> all = queryAll('*');
-      List<CanvasElement> canvases = all.where((e) => e is CanvasElement);
+      Iterable<CanvasElement> canvases = all.where((e) => e is CanvasElement);
       for (var e in canvases) {
         expect(e is CanvasElement, isTrue);
       }
       expect(canvases.length, equals(2));
     });
 
   test('node.queryAll', () {
       List<Element> list = div.queryAll('*');
       expect(list.length, equals(5));
       expect(list[0], isDivElement);
       expect(list[1], isCanvasElement);
       expect(list[2], isDivElement);
       expect(list[3], isDivElement);
       expect(list[4], isCanvasElement);
     });
 
   test('immutable', () {
       List<Element> list = div.queryAll('*');
       int len = list.length;
       expect(() { list.add(new DivElement()); }, throwsUnsupportedError);
       expect(list.length, equals(len));
     });
 }