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

test/codegen/lib/html/wrapping_collections_test.dart

Index: test/codegen/lib/html/wrapping_collections_test.dart
diff --git a/test/codegen/lib/html/wrapping_collections_test.dart b/test/codegen/lib/html/wrapping_collections_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..218d255b46a456c3a602f3c65e6abe651f9a30c7
--- /dev/null
+++ b/test/codegen/lib/html/wrapping_collections_test.dart
@@ -0,0 +1,27 @@
+library wrapping_collection_test;
+
+import 'dart:html';
+import 'dart:html_common';
+import 'dart:js' as js;
+import 'package:unittest/unittest.dart';
+import 'package:unittest/html_config.dart';
+
+/// Test that if we access objects through JS-interop we get the
+/// appropriate objects, even if dart:html maps them.
+main() {
+  test("Access through JS-interop", () {
+    var performance = js.context['performance'];
+    var entries = performance.callMethod('getEntries', const []);
+    entries.forEach((x) {
+        expect(x is js.JsObject, isTrue);
+    });
+  });
+
+  test("Access through dart:html", () {
+    var dartPerformance = js.JsNative.toTypedObject(js.context['performance']);
+    var dartEntries = dartPerformance.getEntries();
+    dartEntries.forEach((x) {
+        expect(x is PerformanceEntry, isTrue);
+    });
+  });
+}