anchor.diff:      if (_layoutTemplate == null) {
         final ui.ParagraphBuilder builder = new ui.ParagraphBuilder(
           _createParagraphStyle(TextDirection.rtl),
  -      ); // direction doesn't matter, text is just a zero width space
  +      ); // direction doesn't matter, text is just a space
         if (text?.style != null)
           builder.pushStyle(text.style.getTextStyle(textScaleFactor: textScaleFactor));
  -      builder.addText(_kZeroWidthSpace);
  +      builder.addText(' ');
         _layoutTemplate = builder.build()
           ..layout(new ui.ParagraphConstraints(width: double.infinity));
       }
  
positive.code:     );
    }
  
    /// The height of a zero-width space in [text] in logical pixels.
    ///
    /// Not every line of text in [text] will have this height, but this height
    /// is "typical" for text in [text] and useful for sizing other objects
  
negative.code: import 'text_span.dart';
  
  export 'package:flutter/services.dart' show TextRange, TextSelection;
  
  /// An object that paints a [TextSpan] tree into a [Canvas].
  ///
  