Fix up dromaeo after lib v2 merge and add Dromaeo smoketest to prevent future

samples/third_party/dromaeo/tests/dom-query-html.dart

Index: samples/third_party/dromaeo/tests/dom-query-html.dart
diff --git a/samples/third_party/dromaeo/tests/dom-query-html.dart b/samples/third_party/dromaeo/tests/dom-query-html.dart
index 242cb29bb63c8ee87a6c52a8193a974a56c86313..8cc6899b29059077e572188efbac7bc0de6e4a6c 100644
--- a/samples/third_party/dromaeo/tests/dom-query-html.dart
+++ b/samples/third_party/dromaeo/tests/dom-query-html.dart
@@ -1,6 +1,7 @@
 library dromaeo;
 import 'dart:html';
 import '../common/common.dart';
+import 'dart:json' as json;
 import 'dart:math' as Math;
 part 'Common.dart';
 part 'RunnerSuite.dart';