anchor.diff:    }
   
     List<int> _indexComponents() {
  +    _checkEmptyInput();
       int savedByteOffset = _byteOffset;
       _byteOffset = _bytes.length - 4;
       List<int> index = <int>[];
  
positive.code:   ///
    /// The input bytes may contain multiple files concatenated.
    void readComponent(Component component, {bool checkCanonicalNames: false}) {
      // Check that we have a .dill file and it has the correct version before we
      // start decoding it.  Otherwise we will fail for cryptic reasons.
      int offset = _byteOffset;
  
negative.code:     return new List.from(index.reversed);
    }
  
    void _checkEmptyInput() {
      if (_bytes.length == 0) throw new StateError("Empty input given.");
    }
  
    /// Deserializes a kernel component and stores it in [component].
    ///
    /// When linking with a non-empty component, canonical names must have been
  