anchor.diff:     */
     TaskManager get taskManager {
       if (_taskManager == null) {
  -      if (enginePlugin.taskExtensionPoint == null) {
  -        // The plugin wasn't used, so tasks are not registered.
  -        new ExtensionManager().processPlugins([enginePlugin]);
  -      }
  +      new ExtensionManager().processPlugins(supportedPlugins);
         _taskManager = new TaskManager();
         _taskManager.addTaskDescriptors(enginePlugin.taskDescriptors);
         // TODO(brianwilkerson) Create a way to associate different results with
  
positive.code:   bool limitInvalidationInTaskModel = false;
  
    /**
     * The task manager used to manage the tasks used to analyze code.
     */
    TaskManager _taskManager;
  
negative.code:    * Perform work until the given [result] has been computed for the given
     * [target]. Return the computed value.
     */
    Object /*V*/ computeResult(
        AnalysisTarget target, ResultDescriptor /*<V>*/ result);
  
    /**
     * Notifies the context that the client is going to stop using this context.
  