Clean-up the registration of plugins

pkg/analysis_server/test/services/completion/optype_test.dart

Index: pkg/analysis_server/test/services/completion/optype_test.dart
diff --git a/pkg/analysis_server/test/services/completion/optype_test.dart b/pkg/analysis_server/test/services/completion/optype_test.dart
index 94b5dafe2c1cc204d83cb2a7038d7ac0f2e8f566..9f2ce434c19d8ee7c3957d0e5384c1c4db57a4ce 100644
--- a/pkg/analysis_server/test/services/completion/optype_test.dart
+++ b/pkg/analysis_server/test/services/completion/optype_test.dart
@@ -14,6 +14,8 @@ import 'package:unittest/unittest.dart';
 
 import '../../abstract_context.dart';
 import '../../utils.dart';
+import 'package:plugin/plugin.dart';
+import 'package:plugin/manager.dart';
 
 main() {
   initializeTestEnvironment();
@@ -24,6 +26,16 @@ main() {
 class OpTypeTest {
   OpType visitor;
 
+  void processRequiredPlugins() {
+    ExtensionManager manager = new ExtensionManager();
+    manager.processPlugins(AnalysisEngine.instance.requiredPlugins);
+  }
+
+  @override
+  void setUp() {
+    processRequiredPlugins();
+  }
+
   void addTestSource(String content, {bool resolved: false}) {
     int offset = content.indexOf('^');
     expect(offset, isNot(equals(-1)), reason: 'missing ^');