using unittest via package import

tests/html/css_rule_list_test.dart

 library CssRuleListTest;
-import '../../pkg/unittest/lib/unittest.dart';
-import '../../pkg/unittest/lib/html_config.dart';
+import 'package:unittest/unittest.dart';
+import 'package:unittest/html_config.dart';
 import 'dart:html';
 
 main() {
 
   var isCssRuleList =
       predicate((x) => x is List<CssRule>, 'is a List<CssRule>');
 
   useHtmlConfiguration();
 
   test("ClientRectList test", () {
     var sheet = document.styleSheets[0];
     List<CssRule> rulesList = sheet.cssRules;
     expect(rulesList, isCssRuleList);
   });
 }