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

tests/html/exceptions_test.dart

Index: tests/html/exceptions_test.dart
diff --git a/tests/html/exceptions_test.dart b/tests/html/exceptions_test.dart
index 388835fc354601e491ef6ad2116b2c18931ece91..01fcd7c078a930565c0fc523bcd53a8d602fd7a4 100644
--- a/tests/html/exceptions_test.dart
+++ b/tests/html/exceptions_test.dart
@@ -10,8 +10,8 @@ main() {
       window.webkitNotifications.createNotification('', '', '');
     } on DomException catch (e) {
       expect(e.code, DomException.SECURITY_ERR);
-      expect(e.name, 'SECURITY_ERR');
-      expect(e.message, 'SECURITY_ERR: DOM Exception 18');
+      expect(e.name, 'SecurityError');
+      expect(e.message, 'SecurityError: DOM Exception 18');
     }
   });
   test('EventException', () {