Clean-up the registration of plugins

pkg/analysis_server/test/analysis_abstract.dart

Index: pkg/analysis_server/test/analysis_abstract.dart
diff --git a/pkg/analysis_server/test/analysis_abstract.dart b/pkg/analysis_server/test/analysis_abstract.dart
index c367665b7177592483304d20a54ae07118449abd..7af9a462a8d86ff25325bad441b007aaad41069e 100644
--- a/pkg/analysis_server/test/analysis_abstract.dart
+++ b/pkg/analysis_server/test/analysis_abstract.dart
@@ -96,21 +96,24 @@ class AbstractAnalysisTest {
   }
 
   AnalysisServer createAnalysisServer(Index index) {
+    //
+    // Collect plugins
+    //
     ServerPlugin serverPlugin = new ServerPlugin();
-    // TODO(pq): this convoluted extension registry dance needs cleanup.
-    List<Plugin> plugins = <Plugin>[
-      serverPlugin,
-      linterPlugin,
-      linterServerPlugin
-    ];
-    // Accessing `taskManager` ensures that AE plugins are registered.
-    AnalysisEngine.instance.taskManager;
+    List<Plugin> plugins = <Plugin>[];
     plugins.addAll(AnalysisEngine.instance.supportedPlugins);
+    plugins.add(serverPlugin);
+    plugins.add(linterPlugin);
+    plugins.add(linterServerPlugin);
     addServerPlugins(plugins);
-    // process plugins
+    //
+    // Process plugins
+    //
     ExtensionManager manager = new ExtensionManager();
     manager.processPlugins(plugins);
-    // create server
+    //
+    // Create server
+    //
     return new AnalysisServer(
         serverChannel,
         resourceProvider,