Wrong text placement with "alignment-baseline"

The X should be drawn centered vertically at the corner of the red rectangle, but is placed on top of the rectangle.

```
<svg id="svg2" version="1.1" preserveAspectRatio="xMidYMid meet" viewBox="0 0 50 50">
  <rect x="10" y="10" width="10" height="10" fill="Red" />
  <text x="10" y="10" font-size="8" text-anchor="middle" alignment-baseline="central">X</text>  
</svg>
```