anchor.diff:      this.softWrap: true,
       this.overflow: TextOverflow.clip,
       this.maxLines,
  -    Widget child
  +    @required Widget child,
     }) : super(key: key, child: child) {
       assert(style != null);
       assert(softWrap != null);
  
positive.code:   /// Creates a default text style for the given subtree.
    ///
    /// Consider using [DefaultTextStyle.merge] to inherit styling information
    /// from a the current default text style for a given [BuildContext].
    DefaultTextStyle({
      Key key,
      @required this.style,
  
negative.code:     bool softWrap,
      TextOverflow overflow,
      int maxLines,
      @required Widget child,
    }) {
      assert(context != null);
      assert(child != null);
  