Add all dart:html tests from the sdk to test/codegen.

test/codegen/lib/html/native_gc_test.dart

+library NativeGCTest;
+import 'package:unittest/unittest.dart';
+import 'package:unittest/html_config.dart';
+import 'dart:html';
+
+var testEvent = new EventStreamProvider<Event>('test');
+
+main() {
+  useHtmlConfiguration();
+
+  test('EventListener', () {
+      final int N = 1000000;
+      final int M = 1000;
+
+      var div;
+      for (int i = 0; i < M; ++i) {
+        // This memory should be freed when the listener below is
+        // collected.
+        List l = new List(N);
+
+        // Record the iteration number.
+        l[N - 1] = i;
+
+        div = new Element.tag('div');
+        testEvent.forTarget(div).listen((_) {
+            // Only the final iteration's listener should be invoked.
+            // Note: the reference to l keeps the entire list alive.
+            expect(l[N - 1], M - 1);
+          });
+      }
+
+      final event = new Event('test');
+      div.dispatchEvent(event);
+  });
+
+  test('WindowEventListener', () {
+    String message = 'WindowEventListenerTestPingMessage';
+
+    Element testDiv = new DivElement();
+    testDiv.id = '#TestDiv';
+    document.body.append(testDiv);
+    window.onMessage.listen((e) {
+      if (e.data == message) testDiv.click();
+    });
+
+    for (int i = 0; i < 100; ++i) {
+      triggerMajorGC();
+    }
+
+    testDiv.onClick.listen(expectAsync((e) {}));
+    window.postMessage(message, '*');
+  });
+}
+
+void triggerMajorGC() {
+  List list = new List(1000000);
+  Element div = new DivElement();
+  div.onClick.listen((e) => print(list[0]));
+}