Make 'where' lazy.

tests/html/queryall_test.dart

Index: tests/html/queryall_test.dart
diff --git a/tests/html/queryall_test.dart b/tests/html/queryall_test.dart
index 4f6d1dafd7f05932feea11fbcb8f88c771676993..6ebce45d7cb5d41321fed7a81d0e56fed5b224d8 100644
--- a/tests/html/queryall_test.dart
+++ b/tests/html/queryall_test.dart
@@ -59,9 +59,9 @@ main() {
       }
     });
 
-  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);
       }