message: fix Width::merge_with_group
diff: @@ -160,8 +160,8 @@ impl<'a> Style<'a> for Width<'a> {
  group.dynamic_css_props.extend(dynamic_css_props);
  let width_mode_class = match width_mode {
  - WidthMode::Exact => "exact_height",
  - WidthMode::Fill => "fill_height",
  + WidthMode::Exact => "exact_width",
  + WidthMode::Fill => "fill_width",
  };
  group.class(width_mode_class)
  }
  