Make 'where' lazy.

tests/html/element_test.dart

Index: tests/html/element_test.dart
diff --git a/tests/html/element_test.dart b/tests/html/element_test.dart
index 1b738bd5c1e1ffdc0d5d7cd2f5f15d5bbbf23b00..bc56ea243b837119504910d7cbc6201ec550ee0b 100644
--- a/tests/html/element_test.dart
+++ b/tests/html/element_test.dart
@@ -505,7 +505,7 @@ main() {
       expect(els[2], isInputElement);
     });
 
-    test('filter', () {
+    test('where', () {
       var filtered = makeElementWithChildren().elements.
         where((n) => n is ImageElement);
       expect(1, filtered.length);
@@ -643,13 +643,13 @@ main() {
       expect(els[2], isHRElement);
     });
 
-    test('map', () {
+    test('mappedBy', () {
       var texts = getQueryAll().mappedBy((el) => el.text).toList();
       expect(texts, equals(['Dart!', 'Hello', '']));
     });
 
-    test('filter', () {
-      var filtered = getQueryAll().where((n) => n is SpanElement);
+    test('where', () {
+      var filtered = getQueryAll().where((n) => n is SpanElement).toList();
       expect(filtered.length, 1);
       expect(filtered[0], isSpanElement);
       expect(filtered, isElementList);
@@ -727,7 +727,7 @@ main() {
   group('_ElementList', () {
     List<Element> makeElList() => makeElementWithChildren().elements;
 
-    test('filter', () {
+    test('where', () {
       var filtered = makeElList().where((n) => n is ImageElement);
       expect(filtered.length, 1);
       expect(filtered[0], isImageElement);