anchor.diff:  int _lastStart = -1;
   int _lastEnd = -1;
   String _lastText = '';
  -ParagraphGeometricStyle? _lastStyle;
  +String _lastCssFont = '';
   double _lastWidth = -1;
   
   /// Measures the width of the substring of [text] starting from the index
  
positive.code:   /// This method uses [_text], [_style] and [_canvasContext] to perform the
    /// measurement.
    double measureSubstring(int start, int end) {
      return _measureSubstring(_canvasContext, _style, _text!, start, end);
    }
  
    /// In a continuous block of text, finds the point where text can be broken to
  
negative.code:     final int chunkEnd = brk.index;
      final double width = _measureSubstring(
        _canvasContext,
        _text,
        _lastChunkEnd,
        brk.indexWithoutTrailingSpaces,
        letterSpacing: _style.letterSpacing,
      );
      if (width > value) {
        value = width;
  