Viewport <#document> at (0,0) content-size 800x600 children: not-inline
  BlockContainer <svg> at (0,0) content-size 800x0 children: inline
    TextNode <#text>
    InlineNode <rect>
    TextNode <#text>

ViewportPaintable (Viewport<#document>) [0,0 800x600]
  PaintableWithLines (BlockContainer<svg>) [0,0 800x0]
    InlinePaintable (InlineNode<rect>)