Fix versions implementation (flutter/engine#7726)

engine/src/flutter/lib/ui/versions.cc

@@ -25,7 +25,7 @@ void GetVersions(Dart_NativeArguments args) {
 }
 
 void Versions::RegisterNatives(tonic::DartLibraryNatives* natives) {
-  natives->Register({{"Versions_getVersions", GetVersions, 1, true}});
+  natives->Register({{"Versions_getVersions", GetVersions, 0, true}});
 }
 
 }  // namespace blink

engine/src/flutter/testing/dart/versions_test.dart

@@ -2,13 +2,10 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// HACK: pretend to be dart.ui in order to access its internals
-library dart.ui;
+import 'dart:ui';
 
 import 'package:test/test.dart';
 
-part '../../lib/ui/versions.dart';
-
 bool _isNotEmpty(String s) {
   if (s == null || s.isEmpty) {
     return false;