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

samples/third_party/dromaeo/tests/dom-attr-htmlidiomatic.dart

-library dromaeo;
-import 'dart:html';
-import 'dart:json' as json;
-import 'dart:math' as Math;
-part 'Common.dart';
-part 'RunnerSuite.dart';
-
-void main() {
-  final int num = 10240;
-
-  // Try to force real results.
-  var ret;
-
-  Element elem = document.query('#test1');
-  Element a = document.queryAll('a')[0];
-
-  new Suite(window, 'dom-attr')
-    .test('getAttribute', () {
-      for (int i = 0; i < num; i++)
-        ret = elem.attributes['id'];
-    })
-    .test('element.property', () {
-      for (int i = 0; i < num * 2; i++)
-        ret = elem.id;
-    })
-    .test('setAttribute', () {
-        for (int i = 0; i < num; i++)
-        a.attributes['id'] = 'foo';
-    })
-    .test('element.property = value', () {
-      for (int i = 0; i < num; i++)
-        a.id = 'foo';
-    })
-    .end();
-}