Revert "Fix test failures on the bots"

pkg/analyzer/tool/task_dependency_graph/generate.dart

Index: pkg/analyzer/tool/task_dependency_graph/generate.dart
diff --git a/pkg/analyzer/tool/task_dependency_graph/generate.dart b/pkg/analyzer/tool/task_dependency_graph/generate.dart
index 5f69b36b14e039695910f809393f2188f347835c..daac1029e21ad5db3c37a4cd1564f0a4267cec0e 100644
--- a/pkg/analyzer/tool/task_dependency_graph/generate.dart
+++ b/pkg/analyzer/tool/task_dependency_graph/generate.dart
@@ -34,7 +34,6 @@ import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/generated/source_io.dart';
 import 'package:path/path.dart' as path;
 import 'package:path/path.dart';
-import 'package:plugin/manager.dart';
 
 /**
  * Generate the target .dot file.
@@ -121,9 +120,6 @@ class Driver {
    * Generate the task dependency graph and return it as a [String].
    */
   String generateFileContents() {
-    ExtensionManager extensionManager = new ExtensionManager();
-    extensionManager.processPlugins(AnalysisEngine.instance.supportedPlugins);
-
     List<String> lines = <String>[];
     resourceProvider = PhysicalResourceProvider.INSTANCE;
     DartSdk sdk = DirectoryBasedDartSdk.defaultSdk;