anchor.diff:      }
     }
   
  -  void forEach(void f(key, value)) {
  +  void forEach(void f(String key, value)) {
       if (_isUpgraded) return _upgradedMap.forEach(f);
       List<String> keys = _computeKeys();
       for (int i = 0; i < keys.length; i++) {
  
positive.code: 
      // Copy all the (key, value) pairs to a freshly allocated
      // linked hash map thus preserving the ordering.
      Map result = <String, dynamic>{};
      List<String> keys = _computeKeys();
      for (int i = 0; i < keys.length; i++) {
        String key = keys[i];
  
negative.code:     }
    }
  
    void addAll(Map<String, dynamic> other) {
      other.forEach((key, value) {
        this[key] = value;
      });
  