anchor.diff:    /**
      * true, if any onException handler handled the exception.
      */
  -  bool _exceptionHandled;
  +  bool _exceptionHandled = false;
   
     /**
      * Listeners waiting to receive the value of this future.
  
positive.code: // Copyright 2011 Google Inc. All Rights Reserved.
  // Dart core library.
  
  class FutureImpl<T> implements Future<T> {
  
    bool _isComplete;
  
    /**
     * Value that was provided to this Future by the Completer
  
negative.code:    */
    final List<Function> _exceptionHandlers;
  
    FutureImpl()
      : _listeners = [],
        _exceptionHandlers = [];
  
    factory FutureImpl.immediate(T value) {
      final res = new FutureImpl();
  