Fix test failures on the bots

pkg/analyzer/tool/task_dependency_graph/generate.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * This file contains code to output a description of tasks and their
  * dependencies in ".dot" format.  Prior to running, the user should run "pub
  * get" in the analyzer directory to ensure that a "packages" folder exists.
  *
  * TODO(paulberry):
@@ skipping 16 matching lines @@
 import 'package:analyzer/src/generated/constant.dart';
 import 'package:analyzer/src/generated/element.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/java_io.dart';
 import 'package:analyzer/src/generated/sdk.dart';
 import 'package:analyzer/src/generated/sdk_io.dart';
 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.
  */
 main() {
   String script = Platform.script.toFilePath(windows: Platform.isWindows);
   String pkgPath = normalize(join(dirname(script), '..', '..'));
   GeneratedContent.generateAll(pkgPath, <GeneratedContent>[target]);
 }
 
@@ skipping 66 matching lines @@
     node.accept(new GetterFinder(resultDescriptorType, resultDescriptors.add));
     for (PropertyAccessorElement resultDescriptor in resultDescriptors) {
       callback(resultDescriptor.name);
     }
   }
 
   /**
    * 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;
     context = AnalysisEngine.instance.createAnalysisContext();
     String packageRootPath;
     if (Platform.packageRoot.isNotEmpty) {
       packageRootPath = Platform.packageRoot;
     } else {
       packageRootPath = path.join(rootDir, 'packages');
     }
@@ skipping 176 matching lines @@
   @override
   visitIdentifier(Identifier node) {
     Element element = node.staticElement;
     if (element is PropertyAccessorElement &&
         element.isGetter &&
         element.returnType.isSubtypeOf(type)) {
       callback(element);
     }
   }
 }