Make browser tests all run from a server instead of the local filesystem.

pkg/intl/test/date_time_format_test_core.dart

Index: pkg/intl/test/date_time_format_test_core.dart
diff --git a/pkg/intl/test/date_time_format_test_core.dart b/pkg/intl/test/date_time_format_test_core.dart
index c275f2910b2458baa7dd1c42e2a7401611e6a64e..71bbf84dfd5314e435ada368298890a3b030ffe9 100644
--- a/pkg/intl/test/date_time_format_test_core.dart
+++ b/pkg/intl/test/date_time_format_test_core.dart
@@ -10,10 +10,10 @@
 
 library date_time_format_tests;
 
-import '../../../pkg/unittest/lib/unittest.dart';
+import 'package:unittest/unittest.dart';
 import 'date_time_format_test_data.dart';
-import '../lib/intl.dart';
-import '../lib/src/date_format_internal.dart';
+import 'package:intl/intl.dart';
+import 'package:intl/src/date_format_internal.dart';
 
 var formatsToTest = const [
   DateFormat.DAY,